1912. The symptoms are unlike spotted fever. For full details of this

tick _vide Bulls._ 105 and 106, U.S. Dept. Agric.] *Dermacentor occidentalis*, Neumann. This tick only occurs in the Pacific Coast region of the United States. Owing to the fact that it frequently attacks man as well as occurring in great abundance in Oregon and California, it is of considerable economic importance. It is spoken of as the wood tick, and in the regions where found is the most common tick to attack man. Hooker, Bishopp and Wood (_Bull._ 106, U.S. Dept. Agric., Div. Ent., 1912, p. 189) state that a number of cases have been brought to their notice where the bite of this tick has caused considerable local inflammation, which in some cases required physicians’ attention. It has been supposed to be connected with Rocky Mountain spotted fever, but it is doubtful if it is concerned in its transmission. The engorged female is steel grey, the dorsum with an olive-green surface colour, which covers the grey except in small spots, giving a mottled appearance. The unengorged males and females are reddish-brown, scutum covered with a whitish bloom, interrupted by many red punctures. The female is 9 by 6·1 by 3·3 mm. to 11·8 by 7·6 by 5·6 mm.; the male 2·8 by 1·6 mm. to 4·2 by 2·3 mm. The larvæ are bluish-grey when engorged, reddish-brown when unengorged. The nymph is light brown, sides of scutum darker, and the intestines dark brown. It is confined to the Coast Range and Sierra Nevada Mountains in California and Oregon and the small mountain range to the south-west. *Dermacentor variabilis*, Say. The American dog tick has also been found on man, but it is of little economic importance as it is easily removed from its host. Genus. *Margaropus*, Karsch. *Margaropus annulatus australis*, Fuller. The so-called Australian cattle tick. Newstead[344] reports this as a great pest to man in Jamaica in its larval stage. Its chief hosts are cattle, horses, goats, sheep, dogs and rabbits. [344] _Ann. Trop. Med. and Par._, 1909, iii, No. 4. *Margaropus microplus*, Canestrini. Recorded by Aragão (_Mem. Inst. Oswaldo Cruz_, 1911, iii, fasc. 2, p. 163) as occurring in larval stage on man in Brazil. Genus. *Rhipicephalus*, Koch. *Rhipicephalus sanguineus*, Latreille, 1804. Syn.: _Ixodes sanguineus_, Latr., 1804; _I. rufus_, Koch, 1844; _Rhipicephalus limbatus_, Koch, 1844; _Rh. siculus_, Koch, 1844; _Rh. stigmaticus_, Gerstäcker, 1873. Spread over almost the entire tropical and sub-tropical regions, occurring in Europe in the South of France and in Italy; it infests dogs and more rarely sheep; oxen, cats, foxes and human beings are also attacked.[345] [345] Neumann, G. L., _loc. cit._, 1897, p. 385. NEUMANN’S TABLE OF SPECIES OF ARGAS. 1 {Body elliptical (sides curved) 2. {Body oblong (sides straight), ending anteriorly { in a point 7. 2 {Body transversely oval _vespertilionis_. {Body elongate oval 3. 3 {Margin of body striated 4. {Margin of body formed by quadrangular areolæ PERSICUS. 4 {Body flat, integument plainly wrinkled 5. {Body tumid, elongate; integument finely { wrinkled; coxæ of fourth pair of legs near { anterior third of body _hermanii_. 5 {Body oval, narrowed anteriorly REFLEXUS. {Body elliptical, blunt, hardly narrowed { anteriorly 6. 6 {Body twice as long as broad _cucumerinus_. {Body hardly longer than broad _transgariepinus_. 7 {Dorsal integument with large polygonal { depressions; tarsi appearing bifid BRUMPTII. {Dorsal integument almost smooth; tarsi not { appearing bifid _æqualis_. The _Argantinæ_ are distinguished from the _Ixodinæ_ by the head, which in the former is situated on the inferior aspect of the cephalothorax, while in the _Ixodinæ_ it projects freely; also by the very short proboscis, the small club-like palpi, the lack of suckers on the legs, as well as by the scutellum, which covers the entire back and is bent up round the borders. Two genera are distinguished: Argas, Latreille, 1796 (Rhynchoprion, Hermann, 1804), and Ornithodorus, Koch, 1844. The species live on mammals, but more especially on birds. Genus. *Argas*, Latreille. *Argas reflexus*, Fabricius, 1794. Syn.: _Acarus reflexus_, Fabricius, 1794; _A. marginatus_, Fabricius, 1794; _Rhynchoprion columbæ_, Hermann, 1804. The European marginated tick, _Argas reflexus_ (length of male 4 mm., breadth 3 mm., length of female 6 to 8 mm., breadth 4 mm.), is of a yellowish colour and has yellowish-white legs. The ingested blood shows red or brown through the intestine, which is provided with blind sacs. It lives in dovecots. It remains hidden during the day and at night crawls on to the sleeping pigeons to suck their blood. It has been observed in France, England, Italy, Germany, and Russia. Persons sleeping near infected dovecots, or in apartments formed from pigeon-lofts, are also attacked, even when the room in question has not been used for sheltering pigeons for years, as “marginated ticks” can live in a fasting condition for a very long time. The bite sometimes gives rise to serious symptoms, such as general erythema and sudden œdema. [Illustration: FIG. 361.--_Argas reflexus_: from the dorsal surface, the intestine showing through the integuments. (After Pagenstecher.)] [This pest more often feeds on the blood of man than is imagined. Blanchard states that he has received them from men’s clothes in Strasburg. Boschulte, of Westphalia, records these parasites in a bedroom inhabited by children and connected with a pigeon-house. The children were bitten during sleep on the hands and feet. The result of the bite was intense itching along the nerves, the bite only being marked by a red spot. In a girl of 14 or 15, vesicles were formed similar to those produced by burns, and in an old man an ulcer formed. Others record painful punctures and persistent œdema produced by this pigeon pest. It was once abundant in Canterbury Cathedral, and often caused much annoyance, I am told, to the worshippers; the ticks falling down from the roof, where they were living, derived from the numerous pigeons that breed in the towers. This Acarus has enormous powers of vitality, living without food for months at a time.--F. V. T.] *Argas persicus*, Fischer de Waldheim, 1824. Of oval form and brownish-red colour. The male measures 4 to 5 mm. in length by 3 mm. in breadth; the female 7 to 10 mm. in length by 5 to 6 mm. in breadth. It frequents the entire north-west and north-east of Persia (the gerib-gez or malleh of the Persians, the miana bug of travellers). It lives concealed in houses and attacks man at night to suck his blood. Its bite is much dreaded, but the serious results may probably be attributed to unsuitable treatment of the wound or its invasion by bacteria. [This tick, sometimes called the tampan and wandlius in South Africa, is mainly a fowl parasite. Fowls and ducks frequently die under its attack, particularly young ones, death being due to loss of blood. This tick remains attached to its host during its larval stage for about five days; it then leaves and moults in concealment. In its subsequent stages it visits its host by night and remains for about an hour only, during which time it distends itself fully with blood. As a nymph it moults twice, not once as do the cattle ticks. This tick and other Argas become larger with each moult, but retain their same general appearance. The female visits the host every now and then, and, between, deposits eggs in sheltered crevices. About fifty to 120 are deposited at once. Four weeks seems a necessary period to intervene between visits to the host, and the interval may be extended to upwards of a year according to Lounsbury.[346] [346] “Report of Government Entomologist, Cape of Good Hope, for 1899,” 1900, p. 33. [It is found in the Sudan, where Balfour has found granules derived from the segmentation of spirilla in their digestive tract. Fantham and Hindl have confirmed this. It has been assumed that these granules carry infection. [Illustration: FIG. 362.--_Argas persicus_: ventral aspect. 7/1. (After Mégnin.)] [This so-called Persian tick, the miana, which is such a scourge to travellers in Persia, appears to infest the huts of natives in that country. It has been sent me from Quetta, where it has invaded houses to such an extent the natives cannot live in them. The virulence of its bite is probably due to the tick transmitting fever germs from natives, probably inured, to strangers, who would be susceptible.--F. V. T.] *Argas brumpti*, Neumann. [Found in Somaliland, by Brumpt, and in the Sudan. This tick attacks man as well as wild animals and produces a painful swelling according to King,[347] but as pointed out by that naturalist it probably relies on other than human food.--F. V. T.] [347] “Fourth Report Wellcome Res. Labs.,” 1911, p. 128. *Argas chinche*, Gervais, 1844. This Acarus, a native of the temperate parts of Colombia, is very troublesome to man. It is probably identical with _A. americanus_, Packard, which infests domestic fowls and turkeys, and occasionally also cattle, and is differentiated from _A. reflexus_ by the sculpturing of the cuticle. Genus. *Ornithodorus*, Koch. Neumann’s SYNOPSIS OF THE GENUS ORNITHODORUS is as follows:-- { Hypostome unarmed; integument in nymph stage and 1 { partly in adult spinulose MÉGNINI. { Hypostome armed with recurved teeth; integument { not spinulose 2. 2 { Camerostome with movable lateral flaps TALAJE. { Camerostome without movable lateral flaps 3. { Anterior border of distal segments of legs with 3 { tubercles or festoons 4. { Anterior border of segments of legs without { tubercles or festoons 8. 4 { Body not much contracted anteriorly 5. { Body pointed anteriorly 7. { Tubercles of distal segments of legs higher than { broad, distant 6. 5 { Festoons of distal segments of legs as broad as { high, contiguous _pavimentosus_. 6 { Eyes present SAVIGNYI. { No eyes MOUBATA. 7 { Eyes present _coriaceus_. { No eyes TURICATA. 8 { Integument with fine radiating wrinkles _lahorensis_. { Integument granular 9. 9 { Tarsi appearing bifid at apex _furcosus_. { Tarsi not appearing bifid at apex 10. { Tarsi of first pair of legs with three dorsal 10 { tubercles, of other legs with one _canestrinii_. { Tarsi without dorsal tubercles or with only one 11. { Tarsi of last three pairs of legs with pronounced 11 { dorsal protuberance _tholozanii_. { Tarsi of legs with indistinct dorsal protuberance _erraticus_. *Ornithodorus moubata*, Murray, 1877. An abundant African tick which is one of the carriers of the spirillum of African relapsing fever and can also carry _Filaria perstans_ (Christy). Its body is oval, yellowish-brown when young, greenish-brown when mature. The integument is covered with mamillose tubercles. No eyes and the stout legs granular above, the tibiæ and tarsi fringed with tubercles on the upper side. Pocock[348] records it from Uganda and German East Africa, Congo and Angola, to Namaqualand and the Transvaal in the south. It is called _bibo_ in Uganda, _moubata_ in Angola, and _tampan_ on the Lower Zambesi. It feeds on animals and birds as well as man. Its bite is very painful. This tick is found in native huts, living in cracks and crevices and in the thatch roofs. [348] “A System of Medicine,” Allbutt and Rolleston, i, pt. 2, p. 195. The female tick infected with the spirillum transmits the infection to the eggs and the next generation. They appear to be able to live without food a long time, and probably live for years. They lay their eggs in masses on the ground or in crevices, and when they hatch they are in the nymph stage with four pairs of legs. _O. moubata_ also occurs in Madagascar with recurrent fever (Lamoureux, _Bull. Soc. Path, exot._, 1913, vi, No. 3, pp. 146–149). *Ornithodorus savignyi*, Audouin, 1827. At one time considered the same as the preceding species, but can be easily separated by the presence of two pairs of eyes. It is widely spread over Africa and has been found in South India and at Aden. In the Sudan it occurs in large numbers. King[349] records that a few miles N.N.E. of Khartoum 370 specimens were collected in two hours under a single tree by a well. It is found in Somaliland, where relapsing fever occurs and no _O. moubata_, which it probably replaces as a transmitter (Drake-Brockman, “Rep. Col. Office,” April 6 and April 16, 1913). It also occurs in Tunis, where the natives call it “tobbiah” (Weiss, _Arch. de l’Inst. Pasteur de Tunis_, 1912, pt. 4, p. 226). [349] “Fourth Report Wellcome Res. Labs.,” 1911, B, p. 129. *Ornithodorus coriaceus*, Koch. Found in Mexico, Paraguay and California. Attacks man. *Ornithodorus talaje*, Guerin, 1849. An eyeless species with somewhat elongate pentagonal body found in Mexico and South America, called the “chinche.” A variety of it (_coniceps_) is found at Venice, etc., and another variety on various islands in the Indian Ocean and South Atlantic. Its bite is very painful to man. *Ornithodorus turicata*, Dugès, 1876. Without eyes. Indigenous in Central America; attacks human beings and pigs. The bite is painful and is often followed by serious consequences. [So virulent is this species that pigs put in an infested sty often die in a night. This “turicatas” of Mexico often reaches 6 mm. in length.--F. V. T.] *Ornithodorus tholozani*, Laboulbène and Mégnin, 1882. Syn.: _Argas tholozani_, Lab. and Még., 1882. Without eyes. Males 4 to 6 mm. in length and 2 to 4 mm. in breadth; females 8 to 10 mm. in length and 4 to 5 mm. in breadth. It especially attacks sheep. Native of Persia and Asia Minor. [This species is reputed as being very dangerous to man. It is locally know as the kéné, or sheep-bug. In its fully gorged state it is deep violet.--F. V. T.] *Ornithodorus mégnini*, Dugès, 1883. Syn.: _Argas mégnini_, Dugès, 1883. Length 8·5 mm., breadth 5·5 mm. Native of Mexico. [Another synonym for this species is _Rhynchoprion spinosum_, Marx. The adult males and females are grey to dark brown, the male somewhat the smaller; female 5 by 3·5 by 2·5 mm. to 10 by 6 by 3·5 mm. The larvæ at the seed tick stage are dark grey, turning to pink, then to a whitish grey when engorged. The nymph when young is blood-red in front, rest pearly white; later they turn reddish-brown. [Intense pain may be caused by its presence in and around the ears. [Two specimens in the nymphal state were taken from the ears of a visitor to Cambridge by Dr. J. Christian Simpson. They were supposed to have entered the ears when the gentleman was camping out in Arizona (_Lancet_, 1901, i, No. 4,052, p. 1198, fig. 3). [This species attacks the horse, ass, dog, cats and oxen, generally around the ears, and also attacks man. It is well known in the United States as infesting the ears of children (_New York Ent. Soc. Journ._, 1893, pp. 49–52). [It occurs in Texas, Arizona, New Mexico and California as well as Mexico, Brazil, and possibly many parts of South America; and recently Bedford (“Sec. Report Div. Vet. Res., S. African Union,” 1912, pp. 343, 344) has shown it to occur at Vryburg and Fauresmith, in the Transvaal, on stock. It also occurs in the Sudan.--F. V. T.] OTHER LITERATURE ON _Ixodidæ_. (1) “Pénétration de l’_Ixodes ricinus_ sous la peau de l’homme,” _Compt. rend. Soc. de Biol._, 1891, xliii, ser. 9, iii, pp. 689–691, R. Blanchard. (2) “Notas sobre Ixodidas brazileiros,” _Mem. Inst. Oswaldo Cruz_, 1911, iii, fasc. 2, pp. 145–195, pls. 11 and 12, Dr. H. de Beaurepaire Aragão. Table of Brazilian Species. (3) “Contribuicão para a sistematica e biolojia dos Ixodidas,” _Mem. Inst. Oswaldo Cruz_, 1912, iv, fasc. 1, pp. 96–120, pls. 2 and 3, Dr. H. de Beaurepaire Aragão. Family. *Tyroglyphidæ.* Very small mites without eyes and without tracheæ, with smooth skin. The males usually have a suctorial pore on either side of the anus, which is used during copulation, or suckers may be found in both sexes near the sexual orifice. The mouth parts form a cone with chelate cheliceræ, and three-jointed pedipalpi; the legs are usually short, have five segments with a terminal claw and suckers, or either one or other of these organs. The numerous species and genera live free and from choice in slowly decomposing vegetable and animal matter (cheese, cereals, flour, sugar, preserves, dried anatomical preparations, bacon, dried fruits and fungi), also in the corners of dwellings, etc.; they incidentally get into or on to man, or are found in chamber utensils and in spittoons; actual parasites are rarely found amongst them. [The chief genera are Tyroglyphus, Rhizoglyphus, Glyciphagus, Aleurobius and Histiogaster. The first three have typical characters referred to, but are distinguished from each other by the two former having the hairs on the dorsum smooth, whilst in Glyciphagus they are hairy, plumose, or feathered. Rhizoglyphus can be told from Tyroglyphus by having claws on the tarsi without any suckers; Tyroglyphus has both claws and suckers. The larvæ are hexapod and may become adult in the usual way by repeated moults, or they enter the so-called hypopial stage. In this the eight-legged nymph becomes quiescent, and during this stage it fixes itself to some insect or other animal by a patch of suckers on the lower surface of the hind end of the body, and is so carried from place to place. The hypopus does not feed and has a hard shell and short legs. When it has reached a new home it moults and development proceeds in the normal way. Canestrini and Kramer treat the _Tyroglyphidæ_ as a sub-family of the _Sarcoptidæ_, calling them sub-family _Tyroglyphinæ_, the other sub-families being _Sarcoptinæ_, _Canestriniinæ_ and _Analsinæ_.--F. V. T.] Sub-family. *Tyroglyphinæ.* Genus. *Aleurobius*, Canestrini. *Aleurobius* (*Tyroglyphus*) *farinæ*, de Geer (part), Koch. The male measures 0·33 mm. in length by 0·16 mm. in breadth; the female 0·6 mm. in length by 0·3 mm. in breadth. These mites possess five pairs of suctorial organs of a light colour; the legs are reddish. Moniez observed them in Lille on the skin of labourers who had been unloading Russian corn. A few of the species generally mentioned under the designation of _Tyroglyphus siro_ are probably the common flour-mite, which also occurs on dry cheese. [The _farinæ_ of de Geer is an Aleurobius described by him in 1778 (“Mém. Hist. Ins.,” vii, t. 5, f. 15, p. 97) as _Acarus farinæ_.--F. V. T.] Genus. *Tyroglyphus*, Latreille. *Tyroglyphus siro*, L., 1756. (Defined by Gervais, 1844.) Male 0·5 mm. in length by 0·25 mm. in breadth; female 0·53 mm. in length by 0·28 mm. in breadth; the males have two suckers on the tarsi of the fourth pair of legs. Penis straight, colour whitish or reddish. *Tyroglyphus longior*, Gervais, 1844. White or yellowish, with two black spots on the abdomen. Male 0·55 mm. in length, 0·28 mm. in breadth; penis bent. Female 0·61 mm. in length and 0·28 mm. in breadth. _T. siro_ and _T. longior_ live on dry cheese, in flour, on dried fruits, etc., and have been occasionally observed in the stools, urine, or pus of human beings, and also on their skin. The so-called vanillismus is to be attributed to these species. [_T. siro_ and _T. farinæ_ of Schrank (non Geer) are the same. They are described under other names, such as _Acarus lactis_, Linn.; _A. favorum_, Herm., etc.; _A. lactis_ in milk, _farinæ_ in flour, and _siro_ in cheese; and as _A. dysenteriæ_, Linnæus (“Syst. Nat.,” ed. 12, pp. 1024–1767).] [Illustration: FIG. 363.--_Tyroglyphus farinæ_: male. Enlarged. (After Berlese.)] [Illustration: FIG. 364.--_Tyroglyphus longior_, Gerv. (After Fum. and Robin.)] It is to these species that a case of dysentery was referred. Rolander, who studied under Linnæus, was attacked by what was called dysentery. The complaint soon gave way to treatment, but eight days after it returned, soon disappeared, but again came a third time. All the time Rolander had been living like the other inmates of the house, who all escaped. Linnæus, aware that Bartholemy had attributed dysentery to insects which he said he had seen, advised his student to examine his stool. The result was that innumerable mites were found to be present. Their presence was easily accounted for by the fact that they were found in numbers in a cup made of juniper wood from which the student alone drank of a night, and they were found to be of the same species. What this species is we do not know. Linnæus called it _Acarus dysenteriæ_, but it was the same as his _Acarus siro_. No records have occurred since. It cannot be, as Latreille supposed, the cheese mite, for they have been eaten by millions since, and it is strange no such case has occurred again. [*Tyroglyphus minor* var. *Castellani*, Hirst, causes the copra itch in persons employed in the copra mills in Ceylon. The skin of the hands, arms, legs and even body becomes covered with pruriginous papules, papulo-pustules and pustules near the head. The eruption begins as a rule on the hands. The mites live in the copra dust. They produce dermatitis. Castellani produced the disease experimentally by rubbing copra dust containing mites on the skin of healthy people. Beta-naphthol ointment (5 to 10 per cent.) proved useful in treatment (_Journ. Trop. Med. and Hyg._, December 16, 1912, Castellani and Hirst).--F. V. T.] Genus. *Glyciphagus*, Hering, 1838. *Glyciphagus prunorum*, Her., and *G. domesticus*, de Geer. The Glyciphagi are differentiated from the Tyroglyphi in that the chitinous hairs on the body are fringed or feathered, and that they lack a furrow dividing the cephalothorax from the abdomen. They live under similar conditions to the Tyroglyphi and are occasionally found on man or in fæces. [Sugar merchants and grocers are frequently troubled by swarms of _G. domesticus_, which leave the stores when being handled, and especially shopmen, who handle sugar kept in small stores for some time. These are the Acari that cause that irritating temporary affection known as “grocer’s itch.”--F. V. T.] *Glyciphagus cursor*, Gervais. Under this name Signor Moriggia figures a horny excrescence of great length growing from a woman’s hand, and containing in its cavities quantities of Acarus. This species is really _G. domesticus_, de Geer. _G. domesticus_ has also been described by Gervais (_Ann. Sci. Nat._, 1841, ser. 2, xv, p. 8) as _G. hippopodes_. *Glyciphagus buski*, Murray.[350] [350] Cooper and Busk’s _Micros. Journ._, 1842, and “Economic Entomology,” Murray, p. 280. [This is a mite found by Busk and named after him by Murray. It was taken from beneath the cuticle of the sole of the foot of a negro in the Seamen’s Hospital Ship on the Thames in 1841, in large sores of a peculiar character confined to the soles of the feet. It appeared that the disease was caused by its burrowing beneath the thick cuticle. The disease was attributed to the wearing of a pair of shoes which had been lent to another negro whose feet had been similarly affected for nearly a year. The negro to whom the shoes were lent came from Sierra Leone. Mr. Busk stated that some water brought by Dr. Stranger from the River Sinoe, on the coast of Africa, contained one nearly perfect specimen, and fragments of others very similar to if not identical with this Acarus. Mr. Busk adds that he had been informed by Staff-Assistant Surgeon P. D. Murray that at Sierra Leone there is a native pustular disease called craw-craw--a species of itch breaking into open sores. [From Busk’s original figure I see no reason to doubt that this is a Glyciphagus.--F. V. T.] Genus. *Rhizoglyphus*, Claparède, 1869. *Rhizoglyphus parasiticus*, Dalgetty, 1901. The _Rhizoglyphii_ are to be recognized by their short legs, which are beset with spines, and by the tarsi, which terminate in a claw. They live on plants, roots and bulbs, especially the bulbs of lilies. [Illustration: FIG. 365.--_Rhizoglyphus parasiticus._ _a._, male; _b._, female. Enlarged. (After Dalgetty.)] This species has been observed on the feet of Indian coolies working in the tea plantations; they produce a skin disease which always commences with blebs between the toes, and which almost always extends to the malleoli, but not beyond. The Acari have an elliptical body, which is grey, but varies from greenish-yellow to greenish-brown when the stomach is full. Eyes are absent. The legs are composed of five segments and terminate with a claw. The males measure 0·18 mm. in length by 0·08 mm. in breadth, and possess genital and anal pores; the females measure 0·2 mm. in length by 0·09 mm. in breadth.[351] [This is also known as coolie itch and is common in Indian tea plantations.--F. V. T.] [351] Dalgetty, A. B., “Water-itch; or Sore Feet of Coolies,” _Journ. Trop. Med._, 1901, iv, p. 73. Genus. *Histiogaster*, Berlese, 1883. *Histiogaster* (*entomophagus?*) *spermaticus*, Trouessart, 1900. The genus Histiogaster, which also approaches the _Tyroglyphinæ_, is characterized by the circumstance that the males possess suctorial pores used in copulation, as well as leaf-shaped appendages at the posterior end of the body. They feed on vegetables, especially on small fungi. [Illustration: FIG. 366.--_Histiogaster_ (_entomophagus?_) _spermaticus_: on left, male; on right, female--both from the abdominal aspect. 200/1. (After E. Trouessart.)] This species has been described by Trouessart,[352] who found numerous specimens, some adult, others in the developmental stage (larvæ, nymphs), and ova, in the fluid removed by puncture from a cyst of the right testis. The males measure 0·25 mm., the females 0·32 mm., and the larvæ 0·1 mm. in length. The author is of opinion that the animal--perhaps a fertilized female--was introduced by a catheter, and, as a matter of fact, it was afterwards found that the patient had once had the catheter passed in India while suffering from pernicious fever. [352] Trouessart, E. R., _Compt. rend. Soc. Biol._, Paris, 1900, lii, pp. 742–744, 893, 894; _Arch. de Par._, 1902, v, pp. 449–459. It would here rather appear to be the case of a facultative parasitism of an otherwise free-living species. _Histiogaster entomophagus_, Laboulbène, is found occasionally in collections of insects feeding on larger species containing much fat; the species also occurs on dry cantharides; it appears to belong to the region of South Europe, where, however, it is widely spread. [Entomophagus occurs all over Europe and in America. It has been described under the following names: _Acarus malus_, Shimer, 1868 (_Trans. Illinois Hort. Soc._); _Dermaleichus mali_, Riley, 1873 (_Rep. Ins. Missouri_, v, p. 87); _Tyroglyphus mali_, Murray, 1877 (“Eco. Ent. Apt.,” p. 275); _T. corticalis_, Michael, 1885 (_Trans. Roy. Micros. Soc._, ser. 2, v, 3, p. 27, figs. 1 to 14); _Histiogaster corticalis_, Canestrini, 1888 (_Prosp. Acarof._, iii, p. 397); _H. aleurophagus_, Sicherin, 1894, Canestrini, _Prosp. Acarof._, vi, p. 815. Trouessart’s species is evidently distinct.--F. V. T.] Genus. *Cheyletus.* *Cheyletus mericourti*, Lab. _Acaropsis mericourti_, Moq. Tand. [This mite has been described from three specimens found in pus which flowed from an abscess in the ear of a naval officer, produced by inflammation of the auditory passage. Where the mites came from we do not know, as they were found near the Bank of Newfoundland. This genus of Acari has enormous mandibles and a peculiar tracheal system; two ungues and appendages to the tarsi.--F. V. T.] Family. *Sarcoptidæ* (Itch Mites). Small mites without eyes and tracheæ, and with delicate, transversely striated cuticle. The mouth parts form a cone, over which the shield-shaped upper lip protrudes; the cheliceræ are chelate; the pedipalpi (or maxillary palpi) have three joints; the legs are short and compact, and composed of five segments; the terminal joints have pedunculated suckers (ambulacra) or a long bristle. The larvæ are six-legged. They live on or under the skin of birds and mammals, on which they produce the skin disease known as scabies, or itch. [The _Sarcoptidæ_ attack the hairs, feathers or epidermis of birds, animals and man, living as permanent parasites. The punctures they produce are followed by the formation of more or less thick crusts or scabs, beneath which the mites live and breed (so called scab, mange and itch). Most are oviparous, some ovoviviparous. The eggs are minute, ovoid, with a thin semi-transparent shell. They incubate in a few days, varying from two to ten or eleven, as a rule. Generally sarcoptic diseases lie dormant in winter and revive in spring and summer in man; but in animals with long wool, such as sheep, they are most active during winter, although revival of active reproduction takes place in spring. [Speaking generally, for the _Sarcoptidæ_ there are three distinct stages in the development of the male, four in the female, as follows:-- [(1) The larva. In this stage only three pairs of legs occur. [(2) The nymph, in which a fourth pair of legs appear, and which thus approaches the adult; but so far no sexual organs occur. Nymphs are of two sizes--the smaller being future males, the larger females. [(3) The next stage in the female is the age of _puberty_, the female now being provided with a vulvo-anal slit; this so-called _pubescent female_ is fertilized by the male. The male then dies. But the female again casts her skin and enters another stage-- [(4) The ovigerous female--the egg-laying female--which has differently modified legs. [The rate at which these Acari breed is very great. Gerlach has found that roughly, in each Sarcopt gallery, a female produces fifteen individuals--ten females and five males--and that the progeny reproduce again in fifteen days. The table given below thus shows that one pair may produce the enormous number of 1,500,000 descendants in three months:-- First generation after 15 days 10 females 5 males Second " " 30 " 100 " 50 " Third " " 45 " 1,000 " 500 " Fourth " " 60 " 10,000 " 5,000 " Fifth " " 75 " 100,000 " 50,000 " Sixth " " 90 " 1,000,000 " 500,000 " = _1,500,000 individuals._ [These _Acarinæ_ are divided into three distinct sub-families, namely the _Cytolichinæ_, _Sarcoptinæ_, _Canestriniinæ_. [The _Sarcoptinæ_ alone interest us here, and of the nine genera the three following are the most important:-- [(1) Sarcoptes, Latreille; Eusarcoptes. [(2) Psoroptes, Gerv.; Dermatodectes, Gerlach; Dermatocoptes, Fürstenberg. [(3) Chorioptes, Gerv.; Symbiotes, Gerlach; Dermatophagus, Fürst.; Sarco-dermatocedes, Del. [The following are the main characters of these three genera:-- [_Sarcoptes_--round or slightly oval; the two posterior pairs of legs being nearly or quite concealed beneath the body; the tarsi end in simple long pedicles, with ambulatory suckers. [_Psoroptes_--oval; the legs are all visible outside the margin of the body; the ambulatory suckers are carried on long triangulated stalks; the male has copulatory suckers and abdominal prolongations. [_Chorioptes_--oval; legs long, thick, all visible; ambulatory suckers very wide, carried at the end of simple, short pedicles. [Sarcoptes make channels or furrows beneath the epidermis, and in these the female lays her eggs. This form of acariasis is thus difficult to cure. It is the cause of human itch (_vide Sarcoptes scabiei_). [Psoroptes do not make sub-epidermic galleries; they live and breed in colonies beneath crusts or scabs formed by the changes they produce in their host’s skin. Sheep scab is a common type of disease produced by Psoroptes. This genus is of little importance as a parasite to man. [Chorioptes live as Psoroptes; they also do not affect man. Otodectes, Can., affecting cats and dogs, and others occur, but do not affect man as far as we know at present (“Demodicidae und Sarcoptidae,” von Professor G. Canestrini und P. Kramer, _Das Tierreich_, 1899).--F. V. T.] Sub-family. *Sarcoptinæ.* Genus. *Sarcoptes*, Latreille. *Sarcoptes scabiei*, de Geer, 1778. Syn.: _Acarus scabiei_, de Geer, 1778; _A. psoricus_, Pallas, 1760; _A. siro_, L., 1778; _Sarcoptes exulcerans_,? Linn., 1758, Nitsch, 1818; _S. hominis_, Raspail, 1834, and Hering, 1838; _S. galei_, Owen, 1853; _S. communis_, Delaf. et Bourg., 1862; _S. scabiei_ var. _hominis_, Mégnin, 1880. The body is oval or nearly circular and whitish in colour, with transverse rows of striæ partly interrupted on the back. There are transverse rows of small bristles on the dorsal surface, and groups of trichomæ on the front, sides and back. There are chitinous hairs at the base of the legs; the two first pairs are provided with pedunculated ambulacra in both sexes, the two posterior pairs terminate each with a long bristle in the female; in the male the third pair of legs terminate in a bristle, the fourth pair with a pedunculated ambulacrum. The anus is situated at the posterior border of the dorsal surface. [Illustration: FIG. 367.--_Sarcoptes scabiei_: female, dorsal aspect. 200/1. (After Fürstenberg.)] At one time numerous species were differentiated, according to the form of the Acarus, the number, position and size of the hairs and spines, even according to the hosts, etc. All these characteristics, however, fluctuate so considerably that absolute differentiation is impossible; the supposed species may be regarded in the same light as Mégnin did, as varieties. It is also hardly possible to distinguish the mite of human scabies (_S. hominis_) from that of a number of domestic animals (_S. squamiferus)_. It is best, therefore, to accept one single species (_S. scabiei_), which may give rise to different races or castes by living in the skin of man and mammals, but can pass from one host to the other. [Canestrini and Kramer, in their monograph of the _Sarcoptidæ_, enumerate eighteen distinct species of this genus, from the dog, goat, camel, horse, ferret, lion, wolf, sheep, pig, etc., and two species parasites of man (_scabiei_ and _scabiei-crustosæ_). There is no doubt that they are distinct species.--F. V. T.] The _S. scabiei_ of man (_S. scabiei_ var. _hominis_) (length of male 0·2 to 0·3 mm., and breadth 0·145 to 0·190 mm.; length of female 0·33 to 0·45 mm., and breadth 0·25 to 0·35 mm.) lives in the tunnels that it excavates in the epidermis, and attacks by preference places with thin skin, such as between the fingers, in the bend of the elbows and knees, in the inguinal region, on the penis, on the mammæ, but may also affect other parts. The tunnels, which vary from a few millimetres to a centimetre and more long, do not run straight, but are somewhat tortuous; the female is found at the terminal end. The tunnels contain the excrement and oval eggs (0·14 mm. in length) of the parasite; the males are rarely met with, as they die off after copulation; the females die after depositing their eggs. The six-legged larvæ hatch out after four to eight days, and after about a fortnight, during which time they change their skins three times and undergo metamorphosis, they begin themselves to burrow. Transmission from person to person rarely is effected through linen, but by direct contact (as in coitus); transmission can be artificially effected on horses, dogs and monkeys, but not on cats. [Illustration: FIG. 368.--_Sarcoptes scabiei_: male, ventral aspect. 200/1. (After Fürstenberg.)] The smaller _S. scabiei-crustosæ_, Fürstenberg, is the cause of the itch that occurs chiefly in Norway; it is not certain whether this is a distinct species of itch mite. [This is quite a distinct species, which is recorded from Germany and France. Mégnin (_Parasitology_, 1880, p. 165) described this as _S. scabiei_ var. _lupi_. The female is 140 µ long, 340 µ broad; the male is 170 µ long by 150 µ broad. In _Science_ (March 3, 1893, p. 125) is recorded that at the Indiana Academy of Science Dr. Robert Hessler referred to “a case of that extremely rare and almost extinct form of itch known as ‘Norway itch,’ the _scabies norvegica_ of Hebra, 1852.” The afflicted man was covered with thick, creamy white, leathery scales; some of these scales measured over an inch in diameter and 1/10 in. thick. A constant shedding of scales went on, a handful being gathered daily. They were found full of mites and eggs and riddled with passages. Under treatment the mites were killed and the skin became normal. Dr. Hessler made a calculation of the number of eggs and mites, amounting to ova and shells 7,004,000, mites in all stages 2,009,000.--F. V. T.] The following forms may be transmitted from DOMESTIC ANIMALS to MAN:-- (1) _S. scabiei_ var. _equi_. Male, 0·2 to 0·23 mm. long, 0·16 to 0·17 mm. broad. Female, 0·40 to 0·42 mm. long, 0·28 to 0·32 mm. broad. The horse is the normal host. (2) _S. scabiei_ var. _ovis_. Male, 0·22 mm. long, 0·16 mm. broad. Females, 0·32 to 0·44 mm. long, 0·24 to 0·36 mm. broad. This mite lives on sheep, and passes over to goats and human beings; it may also be artificially transferred to horses, oxen and dogs.[353] [353] [This mite produces the so-called “black muzzle” of sheep.--F. V. T.] (3) _S. scabiei_ var. _capræ_. Male, 0·24 mm. long, 0·188 mm. broad. Female, 0·345 mm. long, 0·342 mm. broad. On goats, passing from them to horse, ox, sheep, pig and man. On the latter, in contradistinction to the varieties (1) and (2), it produces a severe affection. (4) _S. scabiei_ var. _cameli_. Frequently observed in man, chiefly in Africa. A few cases have been observed in Europe; the affection induced by it is severe. (5) _S. scabiei_ var. _aucheniæ_. Male, 0·245 mm. long, 0·182 mm. broad. Female, 0·34 mm. long, 0·264 mm. broad. It lives on the llama, and may be transmitted to man. (6) _S. scabiei_ var. _suis_. Male, 0·25 to 0·35 mm. long, 0·19 to 0·3 mm. broad. Female, 0·4 to 0·5 mm. long, 0·3 to 0·39 mm. broad. In the domestic pig and wild boar; occasionally also in man. The settlement, however, is usually of short duration. (7) _S. scabiei_ var. _canis_. Male, 0·19 to 0·23 mm. long, 0·14 to 0·17 mm. broad. Female, 0·29 to 0·38 mm. long, 0·23 to 0·28 mm. broad. In the house-dog, and also, not unusually, in human beings. (8) and (9) _S. scabiei_ var. _vulpis_ and _S. scabiei_ var. _leonis_ of the fox and lion have likewise been observed on man. These are all distinct species and should read as follows: _S. canis_, Gerl.; _S. ovis_, Mégn.; _S. equi_, Gerl.; _S. dromedarii_, Gerv. (_cameli_, Mégn.); _S. aucheniæ_, Raill.; _S. suis_, Gerl.; _S. vulpis_, Fürst.; _S. leonis_, Can. *Sarcoptes minor*, Fürstenberg, 1861. Anus situated on the back, legs short, pedunculated ambulacra broad; living on cats (_S. minor_ var. _cati_) and rabbits (_S. minor_ var. _cuniculi_). In cats this mite usually lives in the cervical region, and thence spreads to the ears and head; it usually causes the death of the infected animals; it is easily transferable from cat to cat, is difficult to transmit to rabbits, but once settled on them can easily infect other rabbits. On the other hand, the transmission of the itch mite of the rabbit to the cat does not succeed. In man _S. minor_ induces an eruption that disappears after about a fortnight. [_S. minor_, Fürstenberg, 1861 (“Krätzm.,” viii, p. 218), comes in Railliet’s sub-genus NOTOEDRES, 1893 (“Zool.,” ed. 2, p. 660). Canestrini raised this to generic rank in 1894 (_Prosp. Acarof._, vi, p. 724). [There are three species: (1) _N. notoedres_, Mégnin = _Sarcoptes alepis_, Railliet and Lucet (_Compt. rend. Soc. de Biol._, 1893, xlv, p. 404), and _Sarcoptes notoedres_ var. _muris_, Mégnin (_Parasitology_, 1880, pp. 172–174). This occurs on the black and brown rats and the water-vole. [(2) _N. cati_, Hering, 1838 (_N. acta. ac. Leop._, ii, 18, xliv, p. 605, figs. 9 and 10), = _Sarcoptes minor_, Fürstenberg (“Krätzm.,” 1861, viii, p. 215). Found on the cat in Germany, France, Italy, and Britain. [(3) _N. cuniculi_, Gerlach, 1857, “Krätzm.,” iii, figs. 20, 21. It lives on the rabbit and is found in Germany and France.--F. V. T.] [Illustration: FIG. 369.--_Sarcoptes minor_ var. _cati_: on the left, female (lying on its abdomen); on the right, male (lying on its back). (After Railliet.)] The itch mites of domestic animals, which belong to the genera Psoroptes (= Dermatodectes = Dermatocoptes) and Chorioptes (Symbiotes = Dermatophagus), as a rule do not infest and live on man, even when artificially transmitted. It is, however, possible for this to occur. Moniez (“Traité de par.,” 1896, p. 559) mentions that a species of Chorioptes--probably _Ch. bovis_--had been found on man, as had also _Demodex folliculorum_. This author also includes _Dermatophagoides scheremetewskyi_, Bogdanoff (_Bull. soc. imp. d. natural._, _Moscou_, 1864, xxxvii, p. 341), which has repeatedly been found on man in Moscow and Leipzig (Zürn, _Ber. d. med. Ges._, _Leipzig_, 1877, p. 38), as _Chorioptes bovis_. OTHER REFERENCES TO _Scabies crustosæ_ AND _norvegica_, ETC. (1) “Ein Fall von _Scabies crustosa norvegica_,” _Würzb. med. Zeitschr._, l, pp. 134–139, pl. 3, H. Bamberger. (2) “Ueber die Krätzmilbe (_Acarus scabiei_),” _Notiz. a. d. Geb. d. Nat. u. Heilk._, Weimar (1913), xlii (11), Oct., pp. 161–166 (1834), de Blainville. (3) “Rapport sur le ciron de la gale (_Acarus scabiei_),” _Ann. de Mus. d’Hist. nat._, 1831; _Parasitology_, iv, pp. 213–232, de Blainville. Family. *Demodicidæ* (Mites of the Hair-follicles). Small _Acarina_, elongated in worm-like fashion, with annulated abdomen, and without eyes or tracheæ. The mouth parts consist of a suctorial proboscis and three-jointed palpi; the legs are short, and have three segments with small terminal ungues. The anus is situated on the anterior border of the abdomen; oviparous; the larvæ have six stumpy legs. These mites live in the hair-follicles of mammals. Genus. *Demodex*, Owen. *Demodex folliculorum*, Simon, 1842. Syn.: _Acarus folliculorum_, Sim., 1843; _Demodex folliculorum_, Owen, 1843; _Macrogaster platypus_, Miescher, 1843; _Simonea folliculorum_, P. Gervais, 1844; _Steatozoon folliculorum_, Wilson, 1847. As in _Sarcoptes scabiei_, numerous varieties of this species are known; the form parasitic on man lives in the hair-follicles, the meibomian and sebaceous glands, and hardly ever causes inconvenience; the male measures 0·3 mm. in length and the female about 0·4 mm. in length. The eggs 0·06 to 0·08 mm. in length, 0·04 to 0·05 mm. in breadth, and are thin-shelled. The creatures are always attached with the head end downwards in the parts mentioned; they are most frequent in the sebaceous glands of the face, by the nose, lips and forehead, but they may be present on the abdomen and on other parts of the body. They may occasionally obstruct the excretory gland ducts, thus causing inflammation of the gland (comedones); their agglomeration in the meibomian glands sets up inflammation of the margins of the eyelids. There are generally only a few specimens in a gland. According to some statements Demodex occurs in 50 per cent. of mankind and even in children; they survive the death of their hosts by several days. [Illustration: FIG. 370.--_Demodex folliculorum_ of the dog. (After Mégnin.)] The variety living in the dog (_D. folliculorum_ var. _canis_) is smaller than the variety living in man, and produces a skin disease resembling scabies in these animals. According to Zürn they may also live on man; nevertheless, no other investigator has recorded a similar observation, and attempts at artificial infection have proved negative.[354] [354] [This mite causes what we know in England as red mange in dogs.--F. V. T.] [Ten distinct species of Demodex are given by Canestrini and Kramer (“Demodicidae und Sarcoptidae,” _Das Tierreich_, 1899, vii). The species are certainly distinct. [The species living on the dog (_D. canis_, Leydig, 1844) is cosmopolitan. According to the _British Medical Journal_ (February 22, 1913, p. 407), dog mange may be caught by humans. Whitfield and Hobday describe in the _Veterinary Journal_ seventeen cases which have come under their observation.--F. V. T.] Order. *Pentastomida.* Family. *Linguatulidæ.* _Arachnida_ greatly altered in consequence of their parasitic manner of life; for a long time they were regarded as helminthes. The body is elongated, vermiform, flattened or cylindrical, and more or less distinctly annulated. The head, thorax, and abdomen are not defined from each other (fig. 371). The elliptical mouth, surrounded by a chitinous ring, is situated at the anterior end, on the ventral surface, and the intestine leading straight through the body opens at the posterior end. Two retractile hooks are at the sides of the mouth (fig. 372); these are usually considered to be the terminal joints of two pairs of legs, but it appears to be more correct to regard them as the remains of the antennæ and palpi (Stiles). According to this opinion, the legs in the adult state are completely degenerated. The nervous system is reduced to an œsophageal ring. No organs of sense are recognizable except the papillæ at the anterior end. There are neither organs of circulation nor of respiration.[355] [355] What are designated as stigmata in the Linguatulides are the orifices of sebaceous glands. The sexes are distinct. In the small male the sexual orifice is situated ventrally in the anterior part of the body; in the female it is placed near the anus. The _Linguatulidæ_ lay eggs, and from each egg, after being conveyed into an intermediate host, a four-legged larva, with rudimentary mouth parts, hatches out. It goes through a series of metamorphoses, and passes through a second larval condition, which, however, possesses the essential characteristics of the fully developed form. Sooner or later it migrates during this stage, and reaches its final host, mammal or reptile, in the nostrils or lungs of which the adult _Linguatulidæ_ live. [As adults they live as internal blood feeders in various birds, reptiles and mammals, especially in the nasal and respiratory passages. The larval stage occurs in another host in an encysted condition; this host is usually an animal preyed upon by the species in which the sexual forms are found. The larvæ bore through the walls of the host’s stomach and enter liver and spleen or brain, where they encyst; here they grow until they assume almost the appearance of the adult. These encysted larvæ on being eaten later make their way into the nasal passages and lungs, where they mature. Both adults and larvæ occur in man, as mentioned later. [Three genera are recognized in this family:-- [(1) _Linguatula._--Body flat, annulated. Adults live in the nasal sinus. [(2) _Porocephalus._--Body cylindrical, elongate, with often deeply cut rings. Adult in respiratory organs of snakes, larvæ in animals and man. [(3) _Reighardia._--Cylindrical, but not ringed. Not found in humans.--F. V. T.] Genus. *Linguatula*, Fröhlich. *Linguatula rhinaria*, Pilger, 1802. Syn.: _Tænia rhinaria_, Pilger, 1802; _Polystoma tænioides_, Rud., 1810; _Linguatula tænioides_, Lam., 1816; _Pentastoma tænioides_, Rud., 1819. The male is white in colour, 18 to 20 mm. in length, anterior portion 3 to 4 mm. in breadth, posterior part 0·5 mm. in breadth. The female is of a yellowish colour, 8, 10, or 13 cm. long, anterior part 8 to 10 mm. and posterior part 2 mm. wide. The brownish eggs can be seen in the median line. The body is elongated, rather flat, and exhibits about ninety rings or segments with crenellated borders. The hooks round the mouth are strongly curved and are articulated to a basilar support. Eggs oval, 0·09 µ in length, 0·07 µ in breadth. _L. rhinaria_, in the adult condition, lives in the nasal cavity and frontal sinus of the dog, wolf, fox, horse, goat, and occasionally of man; it causes severe catarrh, epistaxis and suppuration. [Illustration: FIG. 371.--_Linguatula rhinaria_: female. Natural size.] [Illustration: FIG. 372.--Larva of _Linguatula rhinaria_ (_Pentastoma denticulatum_). Enlarged. (After Leuckart.)] _Development._--The ova, which are found in masses in the nasal mucus, already possess an embryo; they are expelled with the nasal secretion, and are swallowed by herbivorous mammals with their food, mostly by hares and rabbits, but also by sheep, goats, oxen, horses, antelopes, fallow deer, pigs, cats, and occasionally also by human beings. The young larvæ hatch out in the stomach; they possess a thickened anterior body with rudimentary mouth parts and two pairs of limbs; the body gradually tapers to a short tail. The larvæ of the _Linguatulidæ_ bore through the intestinal wall and reach the liver, more rarely the mesenteric glands, etc.; they here become encysted and enter a sort of pupal stage in which they lose their limbs; after several moultings and gradual growth the second larval stage, having the appearance of the adult Linguatula, sets in. About five to six months after infection the creatures have become 4 to 6 mm. long, possess eighty to ninety rings, which have a series of fine points on their posterior border; the mouth and intestine are formed, the sexual organs mature and the two pairs of hooks are near the mouth. This larval stage (fig. 372) has been known for a long time, but it was regarded as an independent species of animal, and therefore had a separate name (_Linguatula serrata_, Fr.; _Pentastoma denticalatum_, Rud., etc.). [Illustration: FIG. 373.--_Linguatula rhinaria_: on left, eggs in gelatinous covering, 110/1. On right, first larval stage. 300/1. (After M. Koch.)] Later these Linguatula larvæ make an attempt to escape from their hosts, and this, of course, can only be effected by means of an active migration; they leave the cysts, and according to their respective positions in the abdominal or pleural cavities they reach the bronchi or the intestine, and finally pass out; they may be again sniffed up by dogs and settle in their nasal cavities. Still this outward migration does not appear to be necessary for further development. A portion of the larvæ gain access to the nasal cavities directly through the trachea, and thus herbivorous mammals certainly become directly infected. In most cases the infection of dogs, wolves and foxes, that is, of carnivorous mammals, takes place through consuming the bodies of mammals, or parts of them, such as the liver and lungs, which are affected with the second larval form; in any case most larvæ obtain access first to the stomach of their host, from here they make an active migration through the œsophagus to the oral and nasal cavities, in which they settle. It is possible also that the same larvæ which are free in the oral cavity when the food is being eaten migrate into the nasal cavities. After being stationary a fresh skin is formed and the spine-bearing cuticula are thrown off. The male attains its full size in the fourth, and the female in the sixth month. The duration of life is stated to be from fifteen months to several years. _L. rhinaria_ has been observed in man in the adult as well as in the larval condition (_Pentastoma denticulatum_). Zenker first called attention to the occurrence of the larva in man, having found it nine times in the liver in 168 autopsies. Heschl found it twice in Vienna in twenty autopsies, Virchow found it in Würzburg and Berlin, Wagner in Leipzig (10 per cent.), and Frerichs in Breslau five times in forty-seven autopsies. The parasite is much less frequent in Switzerland. According to Klebs, one case occurs in 900 autopsies, and according to Zaeslin two cases occurred in Basle to 1,914 autopsies. In the Seamen’s Hospital in Kronstadt _P. denticulatum_ has been found six times in 659 autopsies. It was almost always the liver that contained one or a few specimens. The parasite was very rarely found in the kidney or spleen, or encysted in the intestinal wall. The adult _L. rhinaria_ is far more rarely observed in man. A case reported by Landon that related to a blacksmith of Elbing is particularly interesting. This man accompanied the campaign of 1870; he soon, however, fell ill with pains in the liver, accompanied by icterus and intestinal disorders. Soon after the war, and after the symptoms were reduced to icterus and weakness, bleeding of the nose set in and continued with slight intermissions for seven years; an unpleasant sensation of pressure in the left nasal cavity set in, with inflammatory swelling of the mucous membrane. At last, in the summer of 1878, when the pressure in the nose had considerably increased, a Linguatula was expelled from the nose with a violent attack of sneezing, and lived for three days longer in water. The bleeding of the nose then ceased and the patient soon recovered. There can be no doubt that the first illness was connected with the invasion in the liver of numerous larvæ of Pentastoma, and disappeared after their encystment; one or a few of these must subsequently have found its way to the nose and settled there. Genus. *Porocephalus.* *Porocephalus constrictus*, v. Siebold, 1852. Syn.: _Nematoideum hominis_, Diesing, 1851; _Pentastomum constrictum_, v. Sieb., 1852; _Porocephalus constrictus_, Stiles, 1893. Porocephalus is distinguished from Linguatula by its cylindrical body and by certain internal structures. _Porocephalus constrictus_ is at present only known in its larval stage. It is milk white in colour with golden-yellow hooklets. Number of rings, twenty-three. Length 13 mm., breadth 2·2 mm. There are no prickles on the posterior border of the annulations of the body. This species was first discovered by Pruner encysted in the livers of two negroes in Cairo. Bilharz reported two further cases in which the parasites were encysted in the liver and in the mucosa of the intestine; a few other observations have been made by Fenger, Aitken, Giard and Chalmas. Aitken’s report deals with soldiers of the British Colonies in Africa. The parasites were discovered in the liver as well as in the lung, and appear to have been the cause of death in one case (pneumonia, peritonitis). Pruner has found the same parasite also in the liver of the giraffe. It has recently been assumed that _Porocephalus constrictus_ is the larva of _Pentastoma moniliforme_, Diesing, 1835, that attains a length of 70 mm. and lives in the lungs of African Pythonides. The larva is known to have been ejected from monkeys (_Cercopithecus albogularis_, _Cynocephalus maimon_), from the giraffe (_Camelopardalis giraffa_), from a species of hyæna (_Proteles cristatus_), and should be expected to occur frequently in smaller mammals which have been swallowed by African serpents of enormous size. [The three species of _Pentastomidæ_, or tongue worms, found in man are _Linguatula serrata_, Frölich; _Porocephalus armillatus_, Wyman; and _Pentastoma moniliformis_, Diesing. [(1) _Linguatula serrata_ has been referred to under a great number of names.[356] It is a frequent parasite in dogs, oxen and sheep; as an adult in the dog and also in the fox and wolf. The nymphal stage is found in rats, hares, rabbits, the horse, oxen, sheep, goats, pigs, camels, deer, the African and long-eared hedgehogs, porcupine, guinea-pig and peccary. In man it is found in both adult and nymphal stages. Sambon says the nymphal stage is of frequent occurrence, but is usually overlooked. Zenker, who first found it in man, obtained it in nine out of 160 _post-mortems_, usually encysted in the liver. It is then said to be harmless. Landon, in 1878, found the adult in man, the patient suffering from epistaxis for about seven years; in the end during a fit of sneezing the living parasite was ejected through the nostril. This case is of particular interest as it appears to suggest that this Acarid may now and then pass its entire development in the same host, or at any rate may actively migrate from the liver to the nasal cavities after a period of encystment in the liver or elsewhere, which has also been observed in herbivorous animals (_vide_ also p. 526). [356] Synonymy given by Sambon: Adult form, _Ténia lanceolé_, Chabert, 1787; _Ver rhinaire_, Chabert, 1787; _Tænia rhinaris_, Pilger, 1805; _Tænia lanceolata_, Rudolphi, 1805; _Cochlus rhinarius_, Rudolphi, 1805; _Prionoderma rhinaria_, Rudolphi, 1808; _Polystoma tænioides_, Rudolphi, 1809; _Linguatula tænioides_, Lamark, 1816; _Prionoderma lanceolata_, Cuvier, 1817; _Pentastoma tænioides_, Rudolphi, 1819; _Linguatula lanceolata_, de Blainville, 1828; _Linguatula rhinaris_, Railliet, 1885; _Linguatula caprina_, R. Blanchard, 1900. Nymphal form: _Linguatula serrata_, Frölich, 1789; _Tænia capræa_, Abildgaard, 1789; _Tænia caprina_, Gmelin, 1800; _Polystoma serrata_, Goeze, 1800; _Halysis caprina_, Zeder, 1803; _Linguatula denticulata_, Rudolphi, 1805; _Echinorhynchus capreæ_, Braun, 1809; _Tetragulus capriæ_, Bosc, 1810; _Pentastoma denticulatum_, Rudolphi, 1819; _Pentastoma emarginatum_, Rudolphi, 1819; _Pentastoma fera_, Creplin, 1829; _Linguatula ferox_, Gros, 1849. [It is recorded from man in Central America (Darling, _Bull. Soc. Path. exot._, 1912, v, p. 118; and again _Arch. Int. Med._, 1912, v, p. 401), also from Rio de Janeiro (_Mem. Inst. Oswaldo Cruz_, 1913, fasc. ii, p. 125) by Faria and Travassos. [(2) _Porocephalus armillatus_, Wyman, is also known under a variety of names.[357] This species is widely spread over tropical Africa. The adult stage is found in pythons and puff-adders, the nymphal in the chimpanzee, Sykes monkey, mandrill and other monkeys, the lion, leopard, banded ichneumon, Aard wolf, dog, black rat, South African reedbuck and the giraffe. The adult has never been found in man or any mammal. No fewer than sixteen cases of the nymphal form, Sambon tells us, have been found in man, and it is probably much more widespread than at present known. So far it has only been found in the African natives. This species has sixteen to seventeen body rings in the male, eighteen to twenty-two in the female, and the body does not taper as much as in the next species. [357] Adult form as _Linguatula armillata_, Wyman, 1847; _Pentastomum polyzonum_, Hailey, 1856; _Pentastomum armillatum_, Leuckart, 1860; _Pentastomum armillatum_, Diesing, 1864; _Porocephalus armillatus_, Stiles, 1893; _Porocephalus polyzonus_, Stiles, 1893; _Porocephalus moniliformis_, Neumann (in part), 1899. Nymphal form: _Linguatula diesingii_, van Beneden, 1849; _Pentastomum euryzonum_, Diesing, 1850; _Nematoideum hominis_, Diesing, 1851; _Pentastomum constrictum_, von Siebold, 1852; _Linguatula constricta_, Küchenmeister, 1855; _Pentastoma leonis_, Wedl., 1863; _Pentastoma fornatum_, Cobbold, 1879; _Pentastomum protelis_, Hoyle, 1883; _Porocephalus constrictus_, Stiles, 1893; _Linguatula constrictor_, Galli-Valerio, 1896; _Pentastomum diesingii_, Shipley, 1898. [(3) _Pentastoma moniliformis_, Diesing,[358] is an Oriental species, found in India, Indo-China and South China, and the Malay Archipelago. The adult occurs in both the Indian and reticulated pythons. The nymphal stage has been found in monkeys, the tiger, the civet and the Indian otter. [358] The synonymy is as follows:--Adult form: _Pentastoma moniliforme_, Diesing, 1835; _Linguatule moniliforme_, Mégnin, 1880; _Porocephalus moniliformis_, Stiles. Nymphal form: _Pentastoma fornatum_, Creplin (in part), 1849; _Pentastoma wedlii_, Cobbold, 1866; _Pentastoma aonycis_, Macalister, 1874; _Porocephalus armillatus_, Stiles (in part), 1908. [The nymph has twice been found in man; in one case in the liver of a Filipino, the other in the serous coat of the small intestine of a native of Sumatra. [This species can be told by the female having twenty-nine to thirty-three body rings, the male twenty-six, and the annulations are more bead-like and less prominent than in the African species. [In addition to these three, Sambon thinks it probable that others occur in man.--F. V. T.] OTHER REFERENCES TO _Pentastomidæ_. (1) “Die Wanderung des _Pentastomum denticulatum_ beim Rinde,” _Centralbl. f. Bakt. u. Parasitenk._, Jan. 2, 1889, v (1), pp. 1–5, V. Bates. (2) “Il _Pentastoma moniliforme_, Dies., nella pantera,” _Med.-vet. Torino_, 1877, 4 s., vi (12), pp. 529–532, R. Bassi. (3) “On the Organization and Development of Linguatula (Pentastoma), accompanied with the description of a new species from the abdominal cavity of the mandrill,” _Ann. and Mag. Nat. Hist._, 1848, 2 s. ii (7), 2, pp. 69–70, v. Beneden. (4) “De la _Linguatula ferox_ (_Pentastoma denticulatum_ aut _serratum_),” _Bull. Acad. roy. d. Sci. d. Belg._, 1855, xxii, pt. 1 (1), pp. 4–10, v. Beneden. (5) “Note sur quelques pentastomes,” _Bull. Acad. roy. d. Sci. de Belg._, 1857, 26, 2 s., ii (5), pp. 29–30, v. Beneden. (6) “Ueber das _Pentastoma_ in de gekrösdrusen den Schafe,” _Repert. d. Thierh. Stuttg._, 1861, xxii, pp. 37–38, Collin. (7) “Eine Linguatula aus der Mesenterialdrüse des Schafes und Dromedars als zweites ungesche. Stadium von _Pent. taenioides_,” _Notiz. u. Tagsber. u. d. Geb. d. Nat. u. Heilk._ Jena, 1862, v, pp. 127, 128, Colin. _B._ *INSECTA* (_Hexapoda_). Three separate regions can always be distinguished in the body of insects, namely, the head, thorax and abdomen. The HEAD is a roundish unsegmented capsule and possesses four pairs of appendages. The first pair are the various shaped feelers (antennæ), which are placed on the superior surface of the head next to the eyes; then more ventrally placed a pair of upper jaws (mandibles) without palpi and without articulations; they are powerful masticatory organs.[359] The first pair of lower jaws (maxillæ) are jointed and bear a palpus (palpus maxillaris); the second pair of maxillæ are soldered together and form the lower lip (labium), and likewise carry a palpus labialis on each side. The upper lip (labrum), as well as the other parts (which, however, are only appendages), belong to the mouth, which is really formed of a number of closely united pieces. The mouth parts are modified according to the functions required of them. _Coleoptera_, _Neuroptera_, and _Orthoptera_ have biting or masticatory mouth parts which conform with the scheme described above. In the licking mouth parts of the _Hymenoptera_ the maxillæ and under lip are considerably elongated, while the mandibles retain their form and are used for triturating the food; in the _Lepidoptera_ nearly all the mouth parts are shortened except the maxillæ, which form a long and sometimes spirally rolled suctorial proboscis; the _Diptera_ and _Rhynchota_ have piercing and sucking mouth parts. The mandibles and maxillæ are metamorphosed into needle-like structures, while the suctorial apparatus is formed by the labrum. [359] [The mandibles are only powerful masticatory organs in biting-mouthed insects (_Mandibulata_); in the sucking or piercing-mouthed insects they may be absent, or in the form of needle-like stylets (_Haustellata_).--F. V. T.] The thorax consists of three segments, which are frequently united; ventrally it carries three pairs of legs, which consist of a definite number of articulated pieces joined together. Their form also changes according to their function, so that legs for running, walking, digging, swimming, jumping, and preying are seen. A pair of wings are respectively attached to the last and last but one thoracic rings, and these may be traced back, not to metamorphosed appendages, but to tracheal branchia. They are composed of chitinous membranes supported by branched structures (veins or ribs). Their size and formation vary; they are seldom of equal size and form (_Neuroptera_); often the posterior wings are larger than the anterior wings, the former then only serving as protective coverings for the latter (_Coleoptera_), or the anterior wings are larger (_Lepidoptera_), or the posterior wings are shortened or are entirely absent (_Diptera_); and finally there are insects in which both pairs of wings are lacking.[360] [360] [As in the order _Aptera_, which includes the Thysanura and Collembola, and also exceptions in other orders, as the fleas amongst _Diptera_, the Mutillus and ants amongst _Hymenoptera_.--F. V. T.] The abdomen retains its segmentation, but, with the exception of a few groups related to the primitive forms of insects, has no appendages in the imago condition; the abdomen usually consists of ten segments, on the last of which the anus is situated. We need only observe the following characters in considering the anatomy of insects:-- The EPIDERMIS consists of the chitinous cuticle, which is separate from the cellular layer beneath (hypodermis); the various appendages are supported by the chitinous layer. The INTESTINAL CANAL usually consists of the anterior, median and terminal intestine, and as a rule passes straight through the body; salivary glands discharge into the anterior part, and, in some cases, yield a stiffening secretion which serves for spinning webs; numerous or scanty hepatic tubes are appended to the median intestine, while on the border between the median and terminal intestine open four to six long tubes (vasa malpighiana), which act as urinary organs. Finally the end portion of the intestine carries various glands (anal and rectal glands, etc.). The CENTRAL NERVOUS SYSTEM agrees in structure with that of the Annelids, but is more highly developed. The pharyngeal ring surrounds the front part of the intestine; the sensory nerves originate from its SUPERIOR PHARYNGEAL GANGLIA and are the seat of the higher psychical functions; the INFERIOR PHARYNGEAL GANGLIA govern the mouth parts, and in addition appear to regulate the movements (cerebellum) of the vertebrates. The chain of GANGLIA lying on the ventral side of the abdomen consists primitively of pairs of ganglia corresponding with the twelve segments, which are connected by longitudinal and transverse commissures. But many changes in the ganglia may be seen in insects caused by partial or entire amalgamation of single ganglia, so that in a few cases only one abdominal ganglion is present. In conclusion, a definite INTESTINAL NERVOUS SYSTEM is always present. Of the organs of sense the FACETTED EYES, situated at the sides of the head, deserve special mention, as do also the ORGANS OF TOUCH and SMELL, situated on the antennæ, and the ORGANS OF HEARING and taste, or finer sensations, situated at the mouth and in the buccal cavity. The sounds emitted by insects are, as a rule, produced by the friction or beating of certain chitinous parts, but sounds are also produced in breathing (flies). The ORGANS OF RESPIRATION, the so-called tracheæ, are highly developed; there are openings (stigmata) at the sides of the body which draw in air by means of the active participation of the muscles of the body. The number of stigmata varies between two and ten pairs; the tracheæ themselves branch off from the trunks in the most varied manner, and carry air to the internal organs. The colourless BLOOD circulates between the tissues and organs, and is kept circulating by the contraction of a chambered dorsal vessel provided with ostia, and which terminates in a short aorta opening at the anterior end. Insects are SEXUALLY DISTINCT; their sexual glands are in pairs and have a tubular structure, but the testicular tubules are united together by a capsule into an oval testicle; exceptionally, also, the excretory canals are double, as also the sexual orifices; usually the paired canals unite into a single oviduct or spermatic duct which terminates at the posterior end of the body after receiving the products of various glands. As to the HISTORY OF THE DEVELOPMENT of insects, all that is necessary to mention here is that the young hatched from eggs only exceptionally (as in _Apterygota_) resemble the adult parent (insecta ametabola); as a rule they differ from them not only in the shape of the body, but also more or less by their manner of life, and only attain the form of the parent through METAMORPHOSIS. This is a gradual process (insecta hemimetabola) in the _Rhynchota_ and _Orthoptera_, or a sudden one with a stage of inanition (insecta metabola) in the other orders. This stage of rest or inanition, the PUPA, concludes the larval life (caterpillar, maggot, etc.); during the pupal stage no nourishment at all is taken, but the internal organs undergo changes; in some forms the rest is not absolute, as voluntary local movements may take place (pupæ of gnats). The insects are divided into numerous orders according to the form of the mouth parts, the structure of the wings, as well as the manner of the development; with the exception of the lowest group (_Apterygota_), which is most nearly related to the ancestors of the insects, and which has no wings and undergoes no metamorphosis, all the remaining orders, which are termed _Pterygota_, have wings on the thorax, though there are, of course, a few species and families of this group which have lost their wings. The _Pterygota_ include-- (1) _Orthoptera._--Biting mouth parts, anterior wings leathery, posterior wings thin, folded longitudinally; metamorphosis incomplete (grasshoppers, crickets, cockroaches). (2) _Pseudoneuroptera._--Biting mouth parts, wings of equal size, thin, not folded up (dragon-flies, hair and feather lice, termites). (3) _Rhynchota_ or _Hemiptera_.--Mouth parts formed for puncturing and sucking; wings alike, or the anterior wings may be thickened, parchment-like at their base (plant lice, cicadæ, bugs and true lice). (4) _Neuroptera._--Biting mouth parts; wings alike, thin; metamorphosis complete (ant-lions, lace-wing flies, etc.). (5) _Trichoptera._--Licking mouth parts; anterior wings narrow, posterior wings longitudinally folded, both ornamented with little hairs; the larvæ are worm-like in form, live in water, and breathe through tracheal gills (may flies, etc.). (6) _Lepidoptera._--Suctorial mouth parts; wings covered with scales (butterflies). (7) _Coleoptera._--Biting mouth parts; anterior wings thickened and differ in colour, appearance and function from the thin, folded posterior wings (beetles). (8) _Hymenoptera._--Mouth parts for licking and biting; the wings alike, membranous (ichneumon flies, ants, wasps, bees, humble bees). (9) _Diptera._--Mouth parts formed for puncturing, sucking or licking; posterior wings degenerated (gnats, flies, gadflies, fleas). (10) _Strepsiptera._--Anterior wings shortened; the female without wings and living parasitically (fan-wings). The parasites of man occur amongst the _Rhynchota_, _Coleoptera_, and amongst the _Diptera_. [The most usual and recent classification of the _Hexapoda_ is the following:-- (1) _Aptera._--Wingless insects; scarcely any metamorphosis. (2) _Neuroptera._--Four membranous wings, frequently with much network; the front pair not much, if at all, harder than the under pair; the latter with but little or no fan-like action in closing; mandibulate; metamorphosis variable, but rarely complete. (3) _Orthoptera._--Four wings; front pair coriaceous or leather-like, usually smaller than the other pair, which are of more delicate texture and contract in repose like a fan; mandibulate; metamorphosis complete. (4) _Thysanoptera._--Four very narrow fringed wings; mouth imperfectly suctorial; metamorphosis slight. (5) _Hemiptera._--Four wings; the front pair either all transparent or with the basal half leathery; mouth suctorial; metamorphosis slight. (6) _Diptera._--Two membranous wings only; mouth suctorial, very varied; metamorphosis complete. (7) _Lepidoptera._--Four large wings covered with scales; mouth suctorial, metamorphosis great. (8) _Hymenoptera._--Four membranous wings; front pair larger than hind, which do not fold up in repose; mandibulate, sometimes with a tubular proboscis; metamorphosis complete. (9) _Coleoptera._--Four wings, the front pair hard and horny (elytra), meeting in a line over the back and covering the delicate hind pair; mandibulate; metamorphosis complete. [There are two other well-known arrangements, namely, Packard’s and Brauer’s, of recent date, but the one given here, which is based on Linnaeus’ grouping by Dr. Sharp, is by far the simplest.--F. V. T.] Order. *Rhyncota.*[361] [361] [Usually known as _Hemiptera_. There are two sub-orders, _Heteroptera_ and _Homoptera_. The former have the base of the front wings coriaceous; the latter have all four wings membranous. The _Homoptera_ are Aphides or plant lice and scale insects (_Coccidæ_), none of which attack man. Recently an interesting case has been reported to me where certain Aphides had been passed in human urine. One species was _Rhopalosiphum dianthi_, the other found in the urine was the hop aphis (_Phorodon humuli_). I cannot believe, however, that they had been actually passed, in spite of the case being reported by a medical man.--F. V. T.] The lower lip forms a long thin tube that can be turned back (rostrum), and within which lie the setaceous mandibles and maxillæ; the first thoracic segment is not united with the two posterior ones; the anterior wings are usually leathery as far as the centre. (_a_) RHYNCOTA APTERA PARASITICA. Family. *Pediculidæ* (Lice). The lower lip is transformed into a projecting rostrum provided with barbed hooklets in which the hollow extensile sucker (maxillæ and mandibles) is situated; no wings; no metamorphosis; only simple eyes; the antennæ are five-jointed, the feet possess hook-like terminal structures; the barrel-shaped eggs (nits) are deposited on the hair of the host. [The lice or _Pediculidæ_ are also known as _Anoplura_ and _Siphunculata_. [They have been split up into a number of families and sub-families and a number of genera, but as far as this work is concerned it is best to retain the single family _Pediculidæ_. [Only the three species mentioned here are common parasites of man, but now and then horse and cattle and sheep lice, _Hæmatopinus_, may cause transitory annoyance.--F. V. T.] Genus. *Pediculus*, Linnæus. *Pediculus capitis*, de Geer, 1778. Male 1 to 1·5 mm. in length, female 1·8 to 2·0 mm. in length. The colour varies from light grey to black according to the colour of the hair of the human race upon which they are parasitic. The abdomen has eight segments, of which the six central ones are each provided with a pair of stigmata. The thorax is as broad as the abdomen. Eggs 0·6 mm. in length; about fifty are deposited by a female head louse. The young can propagate when eighteen days old. The head louse lives especially in the hairy parts of the head of human beings; more rarely it is found on other hairy parts of the body. It is spread over the entire surface of the globe, and was present in America before the arrival of Europeans. Quite exceptionally it is said that it bores itself deep into the epidermis and can live in ulcers. [The eggs are pear-shaped and are attached to the hairs near the roots by means of a clasping collar. They hatch in about seven days. The young are like the adults and mature in a month. Its general colour varies with that of its host. In West Africans nearly black, in Hindoos dark and smoky, on Chinese and Japanese yellow, on Hottentots orange, on South American Indians dark brown (Murray).--F. V. T.] [Illustration: FIG. 374.--Mouth parts of _Pediculus vestimenti_. Enlarged. (After Denny.)] [Illustration: FIG. 375.--Ovum of the head louse. 70/1.] [Illustration: FIG. 376.--Head louse, male. 15/1.] [Illustration: FIG. 377.--_Pediculus vestimenti_, Burm.: adult female. 15/1.] *Pediculus vestimenti*, Nitzsch, 1818. The head in front is somewhat rounded. Antennæ longer than in the head louse; 2 to 3·5 to 4 mm. in length; whitish-grey; the abdomen is broader than the thorax; stigmata as in _P. capitis_. Eggs 0·7 to 0·9 mm. in length; about seventy are deposited. _P. vestimenti_ lives on the neck, throat and trunk of persons, and the clothing next the body, in which also the eggs are deposited. The louse of so-called pedicular disease (_P. tabescentium_) is, according to Landois’ researches, only the usual _P. vestimenti_; moreover, many cases of phthiriasis are attributable to mites or fly maggots. [This parasite has often been a great pest amongst soldiers during long campaigns, especially amongst the Russians during the Crimean War. _Vide_ also notes in Addenda (p. 615) under “Body, Head and Clothes Lice.”--F. V. T.] Genus. *Phthirius*, Leach. *Phthirius inguinalis*, Redi, 1668. Syn.: _Pediculus pubis_, L. Male 0·8 to 1·0 mm. in length; female 1·12 mm. in length; colour greyish-white; form subquadrate; the two posterior pairs of legs are strong; the abdomen has nine segments and six pairs of stigmata; and still another pair of stigmata is situated between the two anterior limbs. Eggs pear-shaped, 0·8 to 0·9 mm. in length, 0·4 to 0·5 mm. in breadth, and are deposited in rows of about ten on the hairs. [Illustration: FIG. 378.--_Phthirius inguinalis_, Leach: they are distinguished by the larger tracheal trunks originating from the stigmata. Enlarged.] _Pediculus pubis_, which is found almost exclusively in the Caucasian race, lives on hairy parts of the body, but hardly ever on the skin of the head; the pubic region is its favourite place of abode. [This species reproduces more rapidly than other lice, and is communicated much more freely. The eggs are often laid singly attached to the hairs near their apex. It is known as the “crab louse.”--F. V. T.] (_b_) RHYNCOTA HEMIPTERA. Family. *Acanthiadæ.* Body flattened, antennæ four-jointed, rostrum three-jointed, wings atrophied. [This family, the _Cimicidæ_, includes the bed bugs; the proboscis, which lies in a groove, is of three segments; the front wings are shown by two small elytra, there is no trace of hind wings. Two species are known commonly to attack man.--F. V. T.] Genus. *Cimex*, Linnæus. *Cimex lectularius*, Linnæus. Syn.: _Acanthia lectularia_, Fabricius, 1794. It measures 4 to 5 mm. in length, 3 mm. in breadth; brownish-red; eight abdominal segments. The female deposits fifty whitish eggs at a time (1·12 mm. in length) three or four times a year; the entire development up to complete maturity takes about eleven months. [They will breed all the year round, but less so in cold weather.--F. V. T.] [Illustration: FIG. 379.--Head of the bed bug from the ventral surface. _a_, the rostrum; _b_, the antenna; and _c_, the eye. 70/1.] The bed bugs live in the cracks and fissures of human habitations, under carpets, behind pictures, in furniture, bedsteads, etc.; hidden during the day, they attack persons at night to suck their blood. The alkaline secretion of the salivary glands dropped into the wound around the separate bites causes the so-called “wheals.” The bed bugs were known in bygone days by the Greeks (κάριο) and the Romans (cimex). They were first mentioned from Strasburg in the eleventh century, and in England about 1500. [This is the common bed bug of northern latitudes and must not be confused with the tropical bed bug (_C. rotundatus_). The bed bug can migrate from one house to another; this especially takes place when a house is uninhabited. They escape from windows and pass along walls, water-pipes and gutters, and so reach adjoining houses. This noxious pest accompanies man wherever he goes; ships and trains become infested, especially the former. [A characteristic feature in this animal is the peculiar odour it produces, like many others in the same group of insects. This odour comes from a clear, oily volatile liquid secreted by glands in various parts of the body. Although the normal food is man’s blood, the bed bug can subsist upon moist wood, dust and dirt that collects in crevices in floors, walls, furniture, etc. The puncturing mouth consists of a fleshy under lip, within which lie four thread-like hard filaments which pierce the flesh, the blood being drawn up through the beak. [The eggs are oval, white, with a projecting rim around one end, with a lid which is pushed off when the young hatch; they are laid in cracks and crevices in batches of from twelve to fifty. The egg stage lasts from seven to ten days. The larval stage so gradually passes into the adult that one scarcely notices the change; during its growth the skin is cast five times, and at the change the little wing-pads are seen, showing that the adult stage is reached. The young larva is at first pale yellowish-white. It resembles the parent, but has no trace of elytra. Although eleven weeks is said to be necessary for their development, the stages may be gone through much more rapidly; Howard and Marlatt[362] give seven weeks in some instances. It seems pretty certain that these Cimex only take one meal of blood between each moult and another preceding egg laying.--F. V. T.] [362] “Household Insects,” Howard and Marlatt, _Bull._ 4 (N.S.), U.S. Dept. Agric., 1896, p. 37. *Cimex rotundatus*, Signoret, 1852. [This bug is common in warm climates; it is an abundant insect in India, and King has found it in the Sudan, where _C. lectularius_ is, however, the common species. It is usually known as the tropical bed bug. Signoret’s bug can be told from the other common species by the shape of the pronotum. In _C. rotundatus_ it is uniformly convex, whilst in _C. lectularius_ the lateral edges are flat and sometimes even concave. The abdomen of _rotundatus_ is also rather more elongate. [This species is of considerable importance, as according to Patton it may act partly as the intermediary host of the piroplasma of kala-azar. [Wenyon found at Bagdad that _Cimex_ sp. would take up Leishmania from Oriental sore, and that the parasite developed into flagellate form. Patton came to the conclusion that the bed bug transmitted Oriental sore in Cambay, India, but Wenyon contests this view (_vide Journ. Lond. School Trop. Med._, 1912, ii, pt. 1, pp. 13–26). Franchini (_Bull. Soc. Path, exot._, 1912, v, No. 10, pp. 817–819) was unable to connect Cimex with this disease. At present nothing seems proved. Besides their possible connection with kala-azar, it has been shown by Howard and Clark (_Journ. Exp. Med._, 1912, xvi, No. 6, pp. 850–859) that they can carry the virus of poliomyelitis. [This bed bug was originally described from the Island of Réunion in 1852 by Signoret. A similar insect was described from Burma by Fieber, in 1861, as _C. macrocephalus_. This is the same as Signoret’s species. [The distribution given by Patton[363] is as follows: India, Burma, Assam, Malay, Aden, Islands of Mauritius and Réunion. Patton in this paper refers to an erroneous statement made in a recent edition of this book (the last English edition). As I have personally kept _lectularius_ in moist dirt, wood and refuse for over two years, the statement as far as I am concerned is not erroneous. Moreover, since his doubting this fact the same experiment has been twice repeated with the same results. What they did and do persist on I cannot say.--F. V. T.] whilst collecting them. It is rounder and has shorter antennæ than [363] _Indian Med. Gaz._, February, 1907, xlii, No. 2. *Cimex columbarius*, Jenyns. [This is common in parts of Europe in pigeon nests, and also amongst poultry (_vide Report Econ. Zool._ for year ending September 30, 1913, pp. 142–144, Theobald). It occurs in Britain on the latter and will attack man. I have personally been badly bitten _C. lectularius_. Jenyns also described a more pubescent species from swallows as _C. hirundinis_. I have recently received an account of the swallow bug invading a house in Kent and causing much annoyance.--F. V. T.] *Cimex ciliatus*, Eversmann, 1841. 3·3 mm. in length, yellowish-red, thickly covered with hair; indigenous in Russia (Kasan). [From a single specimen seen it is evidently distinct.--F. V. T.] Family. *Reduviidæ.* Head long, narrowed behind into a neck; eyes large, prominent; rostrum thick and curved; antennæ moderately long, slender at the tip; legs long and stiff; carnivorous. Amongst the _Reduviidæ_ one genus is of particular importance, namely the genus Conorhinus, which has a long head and the first segment of the beak very much shorter than the second, and the posterior tibiæ longer than the femora. These large bugs have a wide distribution, the Oriental region, North and South America, and the West Indies, Madagascar and West and Central Africa. These large bugs may cause very nasty wounds by their bites, but beyond that it has recently been shown that one interposes in the life-cycle of a trypanosome, namely-- Genus. *Conorhinus*, Lap. *Conorhinus megistus*, Burm. This large bug has recently been shown by Chagas to be the agent in the development of the trypanosome (_T. cruzii_) which is the cause of the well-known disease in many parts of Brazil called _Barbeiro_ (Barbier). This insect is about 1 in. long, black, with four red spots on the pronotum, and six red lateral lines on the abdomen, black legs, head and beak. The insect is figured in a coloured plate (No. 9) in _Mem. Inst. Oswaldo Cruz_, 1909, i, fasc. 2, pp. 158–218. A further account is given by Neiva.[364] [364] _Mem. Inst. Oswaldo Cruz_, 1910, 2, fasc. 2, pp. 206–212. *Conorhinus sanguisuga*, Lec. (Blood-sucking Cone-nose). This bug is also known as the Texas or Mexican bed bug, also as the big bed bug. It is particularly troublesome in the Mississippi Valley in bedrooms. The bite is very severe and results in more pronounced swelling and inflammation than that of the Cimex. Normally this genus feeds upon the blood of mammals and insects. Its fondness for human blood appears to be quite a new habit, and appears limited to the mature insect only. It is nearly an inch long, flat, head very narrow and long, the rostrum short and thick. In colour it is dark brown with pink markings. They are fully winged when adult, and they fly with ease, entering houses on the wing, especially being attracted by lights in windows; they also run swiftly. Like the bed bug they conceal themselves during the day and come out at night and bite the sleeper. The effect of the bite is very varied, but as a rule a sore, itching wound, accompanied by burning pain and swellings, which may extend over a good deal of the body, occur. A specific poison is undoubtedly injected into the puncture; but no doubt serious results are also due to the beak being contaminated through the insects feeding upon foul carrion. Mr. Lembert, when bitten by a _Conorhinus_ sp. (?) on the Pacific slope, exhibited the following symptoms: an itching sensation extending up the leg, large blotches manifesting themselves on the upper part of the limb and extending up to the hands and arms; his lips swelled and the itching and swelling extended over the head; there was also much nausea. Similar results are recorded from other regions.[365] [365] “Household Insects,” p. 42. The eggs of the _C. sanguisuga_ are at first white, then become yellow, then pink; the young hatch in twenty days. There are two larval and two pupal stages, the latter showing wing-pads. The eggs are laid and the young feed out of doors, chiefly upon insects. It is particularly abundant in April and May indoors. *Conorhinus*, _sp. novum_ (Monster Bug). Another species; acts in a very similar way in California, the bite being very poisonous. *Conorhinus rubrofasciatus*, de Geer[366] (Malay Bug). [366] [_First Report Econ. Zool._, 1903, p. 130.--F. V. T.] This large bug attacks man in Malaysia and elsewhere. It is recorded as inflicting “a very nasty sting, which is done by the huge proboscis.” Acute pain and inflammation follow in a few minutes. In one case the whole leg became swollen. This species occurs over the whole Oriental region, in Madagascar and Sierra Leone. It is dark brown in colour with dusky yellow or brick-red markings on the pronotum and elytra. Donovan suggests that it may be connected with the kala-azar piroplasma. *Conorhinus renggeri*, Herr-Schäff (Great Black Bug of Pampas). This large black bug is mentioned by Darwin,[367] who states as follows: “At night I experienced an attack (for it deserves no less a name) of the benchuca, a species of Reduvius, the great black bug of the Pampas. It is most disgusting to feel soft wingless insects, about an inch long, crawling over one’s body. Before sucking they are quite thin, but afterwards they become round and bloated with blood, and in this state are easily crushed. One which I caught at Iquique (for they are found in Chili and Peru) was very empty. When placed on a table, and though surrounded by people, if a finger was presented the bold insect would immediately protrude its sucker, make a charge and, if allowed, draw blood. No pain was caused by the wound. It was curious to watch its body during the action of sucking, as in less than ten minutes it changed from being flat as a wafer to a globular form. This one feast, for which the benchuca was indebted to one of the officers, kept it fat during four whole months, but after the first fortnight it was quite ready to have another suck.” Mr. Kirby[368] also refers to this species. [367] Charles Darwin, “A Naturalist’s Voyage” (Voyage of the _Beagle_), 1888, p. 330. [368] “Text-book of Entomology,” 1885, p. 205. *Conorhinus variegatus* (Variegated Cone-nose). Occurs in Florida in houses, and chases bugs (Cimex) and flies; not definitely known to bite man. *Conorhinus nigrovarius.* This species occurs in South America. It is one of the forms known as bichuque. Its bite makes a troublesome swelling. *Conorhinus protractus.* also attacks man in Utah.[369] It has been called the “big bed bug.” [369] “The Big Bed Bug of the Far West,” _Bull._ 18 (N.S.), _U.S. Dept. Agric._, 1898, p. 101. Genus. *Reduvius, etc.* *Reduvius personatus*, Linné. Syn.: _Reduvius personatus_, Leconte, 1855. European, but also found in the United States. The bite causes intense pain. It bites when caught or handled, but does not seem to do so voluntarily. Swelling and irritation result which may last a week, and may even cause death.[370] In 1899 it was very abundant at Washington and elsewhere; other species occurred, and so no definite opinion existed as to the actual biter, but some people took _R. personatus_ actually biting. It was first described as a parasite of man in America by Walsh and Riley.[371] [370] “Insects to which the name ‘Kissing-bug’ became applied during the summer of 1899,” _Bull._ 22 (N.S.), _U.S. Dept. Agric._, 1900, p. 24. [371] _American Entomologist_, 1869, i, pp. 84–88. A popular name for this bug is the wheel or masked bug--a black insect, three-fourths of an inch long. The larva of this bug is carnivorous and covers its body with dust so as to conceal itself from its prey. The adult is active on the wing. *Coriscus subcoleoptratus*, Kirby, 1837. Syn.: _Nabicula subcoleoptrata_, Kirby, 1837; _Nabis subcoleoptratus_, Reuter, 1872; _Coriscus subcoleoptratus_, Stål, 1873. Northern United States. Howard was bitten by one between the fingers--the pain was intense, like a needle prick, but the swelling was small.[372] No other case known. [372] R. Blanchard, “Sur la Piqûre de quelques Hémiptères,” _Arch, de Par._, 1902, p. 145. *Rasahus biguttatus*, Say, 1831. Syn.: _Pirates biguttatus_, Stål, 1862; _Callisphodrus biguttatus_, Stål, 1866; _Rasahus biguttatus_, Stål, 1872. Common in southern United States, and found in Cuba, Panama and Pará, etc. Known as the two-spotted corsair on account of the great spot on the hemielytra. Frequently found in houses, where it chases the bed bug. It also bites man frequently. From 1869 Walsh and Riley placed it amongst the parasites of man. In the United States Davidson[373] is of opinion that all cases attributed to spider bites are due to this insect. [373] “So-called Spider-bites and their Treatment,” _Therap. Gaz._, February 19, 1875. *Melanolestes morio*, Erichson, 1848 (Non-walker). Syn.: _Pirates morio_, Erichson, 1848; _Melanolestes morio_, Stål, 1866; _Pirates picipes_, Herrich-Schäffer, 1848; _Melanolestes picipes_, Howard, 1900. Guiana and Mexico and eastern and southern United States. Length 20 mm., hides under stones and logs during daylight, and flies at night. Attracted by lights into houses. Very abundant in 1899 at Washington. Howard cites cases where it was proved to bite man. *Melanolestes abdominalis*, Herrich-Schäffer, 1848. Syn.: _Pirates abdominalis_, Herrich-Schäffer; _Melanolestes abdominalis_, Uhler, 1875. Allied to the former; some say similar, but can be told by the shorter wings on the female. It occurs in the same localities as _M. morio_. *Phonergates bicoloripes.* This reduvid attacks man in Africa. Family. *Aradidæ.* Broad and very flat bugs, with antennæ of four segments and the beak of three; scutellum short, no cuneus to elytra and the tarsi of two segments. They normally live under the bark of trees, etc., and are found in most parts of the world. *Dysodius lunatus*, Fabr. (Pito Bug). A large species which is found in South America, frequenting houses, and bites very severely. THE OCHINDUNDU. The bug is described by Wellman (_Journ. Trop. Med._, April 2, 1906, p. 97) as not only feeding on ticks, such as _Ornithodorus moubata_, but as also attacking man. It is called by the Angola Bantus the ochindundu. It is black in colour; the first two pairs of legs are of a bright red hue. It has curious paddle-like structures on the front four legs, which seem to be designed for securely holding the ticks. It infects native kraals for the sake of preying on ticks. The natives also state that it inflicts a bite which far exceeds in painfulness that of the tick. They compare the bite with that of a poisonous snake. Family. *Lygæidæ.* Scutellum short; antennæ four-jointed; ocelli present; membranous part of hemielytra with never more than five nervures. Nearly all vegetable feeders. A few are recorded here as biting man. *Lyctocoris campestris*, Fabricius. Syn.: _Acanthia campestris_, Fabr. (_Lyctocoris domesticus_). Rare in habitations, lives on human blood. Found by Blanchard in a bed at an hotel at Liverpool. The bite is undoubtedly worse than that of Cimex; cosmopolitan. In colour it is ferruginous, shining, legs testaceous; hemielytra slightly shorter and narrower than the abdomen; membranous portion transparent, the apex broadly fuscous. Length 3·8 to 4·8 mm. *Rhodinus prolixus*, Stål, 1859. Sometimes attacks man, and the bite is very painful. It is 25 mm. long and 8 mm. broad, and occurs in Colombia. It is found also in Cayenne and Venezuela. This like other species is known in South America as bichuque or benchuca. [A few other unimportant species are also recorded as biting man, such as _Harpactor cruentas_, in the South of France; _Eulyes amœna_, from Borneo and Java; _Arilus carinatus_, Forster, from Brazil. The latter appears to be the same as the _Acanthia serratus_, Fabricius.--F. V. T.] Order. *Orthoptera.* [The only _Orthoptera_ recorded as doing actual harm to man are certain wingless locusts found in Africa. The cysticercus stage of a small tapeworm found in rats and man has been found in an earwig (Alcock). [The strange _Hemimeridæ_ found in West Africa, resembling wingless cockroaches, are parasitic on rats (_Cricetomys_). _Phasmidæ_, or stick insects, are said to be able to eject a fluid which may cause blindness if it comes in contact with the eyes. LOCUSTS INJURIOUS TO MAN. [A wingless locust--_Enyaliopsis durandi_, Luc--is recorded by Wiggins[374] as injurious to man in Uganda. “The bite of this insect,” it is said, “gives rise to a very nasty eruption, which may extend over the whole body, with high temperature and general malaise. The skin at the site of the bite sloughs away, and generally leaves a large deep cavity, which heals very slowly.” [374] _Bull. Ent. Res._, 1910, i, pt. 3, p. 227. [An allied species--_E. petersi_, Schaum--emits a clear yellow fluid, but according to Marshall this does no harm.[375] Stannus writes that “for some years I have been cognizant of the fact that among the natives of Nyasaland an allied if not the same species is held to cause skin lesions by the emission of a fluid on the bare skin surface of the body. I have seen cases of ulcers on various parts of the body, for which the ‘nantundua’ was assigned as the cause.” He then describes the destruction of the superficial layers of the skin which he observed after the yellow fluid had been on the skin twelve hours.--F. V. T.] [375] _Ibid._, 1911, ii, pt. 2, p. 180. Order. *Coleoptera.* The larvæ of beetles, similarly to those of some other _Arthropoda_ (myriapods and the larvæ of gnats), have sometimes been observed in man as purely accidental guests. In one case or another, such accounts may have originated through a mistake of the observer. Thus English doctors report the presence of the larvæ of _Blaps mortisaga_ in the stools of human beings, Sandberg of the larva of _Agrypnus murinus_ in his ten year old son, and Blanchard mentions the larva of a beetle that was vomited by a child. All these cases, however, do not represent actual parasitism, although there are beetles living parasitically.[376] [376] [Dr. Daniels has sent me a small coleopterous larva found in an abscess on a man in British Guiana.--F. V. T.] *Silvanus surinamensis*, Linnæus (Saw-toothed Grain Beetle). [Taschenberg records this beetle as having invaded some sleeping apartments adjoining a brewery where stores were kept, and annoying the sleepers at night by nipping them when in their beds. [This beetle is common in many parts of the world amongst groceries, corn, meal, seeds, dried fruits, etc. It is about 1/10 in. long, much flattened and chocolate-brown in colour. The thorax has two shallow grooves and bears six minute teeth on each side. The jaws are strong, but the bite cannot be very serious.--F. V. T.] Order. *Diptera* or *Siphonaptera*. *Aphaniptera* (Fleas). Wingless, the thoracic rings distinct and free; antennæ of three segments; legs very powerful; abdomen with nine segments. [Ten segments are present, but only nine are visible.--F. V. T.] The mandibles transformed into serrated puncturing organs, which are situated in the split sheath of the rostrum; the maxillæ are laminated and have palpi, and more or less conceal the other parts. The importance of fleas lies mainly in the fact that they act as plague carriers. About 150 species have already been described. The only ones of importance for this work are those found on man and those on rats and mice. The two families in which these are found are known as _Pulicidæ_ and _Sarcopsyllidæ_. The eggs of fleas are laid on the ground, on rugs, etc., and in birds’ and rodents’ nests. They hatch rapidly in warm weather and in warm climates, varying from two to five days; in cold countries they may take two or three weeks to incubate. The larva is a footless creature, pearly white in colour, the head sometimes being darkened, composed of fourteen segments including the head, and although apodal can move with considerable agility. It lives amongst dust and dirt, and feeds upon any organic matter it can find. In about two weeks it is said to become mature, and then spins a cocoon in which pupation takes place. The cocoons of the common human flea and the fowl flea become covered with dust and dirt. The period of pupal life seems varied, for I have had the fowl flea hatch out in ten days, and others in three weeks at the same time of year. The adults are blood suckers and cause considerable irritation as well as acting as disease carriers, and in the _Sarcopsyllidæ_ the females attach themselves permanently to their hosts, embedding themselves under the skin, where they become pregnant. Some kinds harbour the cystic stage of tapeworms, and the rat trypanosome passes certain stages in the rat flea. Most fleas have definite hosts, but some, like the rat and fowl fleas, attack man. The fleas which can carry the bacillus of plague are _Xenopsylla cheopis_, _Pulex irritans_, _Ceratophyllus fasciatus_ and _Hoplopsyllus anomalus_. The two families, _Pulicidæ_ and _Sarcopsyllidæ_, can be distinguished as follows: Thoracic segments much foreshortened, coxæ and femora of hind legs very slightly enlarged _Sarcopsyllidæ_. Thoracic segments normal, coxæ and femora of all the legs much enlarged _Pulicidæ_. Family. *Sarcopsyllidæ* (Jiggers). The members of this family are not confined to one host. Three genera are known and tabulate as follows:-- α. Hind coxa without a patch of spines on the inside. α^1. Hind femur simple 1. _Dermatophilus._ α^2. Hind femur with a large tooth-like projection near the base 2. _Hectopsylla._ β. Hind coxa with a patch of short spines on the inside 3. _Echidnophaga._ Genus. *Dermatophilus*, Guérin. *Dermatophilus cæcata*, Enderl. The eyes of the female vestigial. Taken on and behind the ears of _Mus rattus_ in Brazil. *Dermatophilus penetrans*, L., 1758 (Jigger, Chigoe). Syn.: _Sarcopsylla penetrans_. About 1 to 1·2 mm. in length; brown in colour. Eyes distinct. The males only occasionally visit man to bite; the fertilized female, on the other hand, bores into the skin with her head, particularly about the toes of the host, and then attains considerable dimensions. The eggs develop on the soil with a metamorphosis similar to that of the common flea. [Illustration: FIG. 380.--_Dermatophilus penetrans_: young female. Highly magnified. (After Moniez.)] [Illustration: FIG. 381.--_Dermatophilus penetrans_: older female. Enlarged. (After Moniez.)] The sand flea (nigua) particularly infests Central and South America, and, in 1873, was carried by ships from Brazil to the West Coast of Africa. In a comparatively short time it has become disseminated throughout Africa and has also appeared in Madagascar; recently also it has been reported from China. Besides attacking man, it also settles on mammals, for instance, on dogs, pigs, etc. According to Jullien the wound or little swelling caused by the female has no particular significance, as children infested with ten or eleven sand fleas quietly proceeded with their games. It will be understood, however, that the wound easily affords the opportunity for the setting up of inflammation or even septic processes, as is the case in any kind of wound. [The jigger is also well known in the West Indies.--F. V. T.] Genus. *Echidnophaga*, Olliff. Four species found on rats, etc. *Echidnophaga gallinacea*, Westwood (Chigoe of Fowls). [This flea is a native of tropical Asia and Africa. It lives on the fowl chiefly, attacking the neck and around the eyes. Specimens were sent me from Texas, where they not only attack poultry but also children, the latter somewhat severely. It also occurs on cats, and is found on rats in Africa. It has been introduced into North America. [Three other species are found on rats, _viz._: _E. myrmecobii_, Rothsch., from Australia; _E. murina_, Tirah, from Southern Europe; and _E. liopus_, Rothsch., India and Western Australia.--F. V. T.] Family. *Pulicidæ* (True Fleas). ROTHSCHILD’S CLASSIFICATION is as follows:-- SECTION I.--Club of antennæ distinctly segmented only on the hind side. _Key to Genera._ _a._ No comb on head and thorax. _a^1._ The internal incrassation, which extends from the insertion of the mid coxa into the thorax, joins the anterior edge of the mesosternite _Pulex_. _b^1._ This incrassation joins the upper edge of the mesosternite _Xenopsylla_. _b._ With a comb on the pronotum only _Hoplopsyllus_. _c._ With a comb on the pronotum and at the lower edge of the head _Ctenocephalus_. SECTION II.--Club of antennæ distinctly segmented all round. _Key to Genera._ _a._ Eye developed. _a^1._ No comb on head. _a^2._ Pygidium not projecting backwards; frons with tubercle _Ceratophyllus_. _b^2._ Pygidium strongly convex, projecting backwards; frons without tubercle _Pygiopsylla_. _b^1._ Two spines at angle of genæ _Chiastopsylla_. _b._ Eye vestigial or absent. _a^1._ Abdomen without comb. _a^2._ Hind edge of tibiæ with about eight short and several long bristles, which do not form a comb. _a^3._ Fifth segment in fore and mid tarsi with five, and in hind tarsus with four bristles _Neopsylla_. _b^3._ Fifth segment in fore and mid tarsi with four, and in hind tarsus with three lateral bristles, there being an additional pair of bristles in all the tarsi on the ventral surface in between the first pair _Ctenophthalmus_. _b^2._ Hind edge of tibiæ with about twelve short and three long bristles, the short ones forming a kind of comb _Ctenopsylla_. _b^1._ Abdomen with at least one comb _Hystricopsylla_. Genus. *Pulex*, Linn. *Pulex irritans*, L., 1758. Male 2 to 2·5 mm. in length, females about 4 mm.; reddish or dark brown; head without bristles; thoracic and abdominal rings of bristles on the dorsal aspect, and small hairs directed backwards at the posterior margin. The barrel-shaped white eggs are deposited in cracks in the boards, sweepings, spittoons, etc.; they produce legless larvæ consisting of fourteen segments, which, after about eleven days, are transformed into pupæ; after another eleven days the flea emerges. [Illustration: FIG. 382.--_Pulex irritans._ 14/1.] [Illustration: FIG. 383.--Larva of flea. Enlarged. (After Railliet.)] [Illustration: FIG. 384.--_Pulex serraticeps._ 22/1.] Fleas live in human dwellings all over the world, and periodically pass on to persons to suck their blood. They may deposit their eggs on very uncleanly individuals, and even undergo development, therefore it is possible to find larvæ and pupæ on such persons. The dog flea, _Pulex serraticeps_, is easily distinguished from the flea of man by the large thick bristles on the posterior margin of the first thoracic ring (fig. 384). Genus. *Xenopsylla*, Glink. *Xenopsylla cheopis*, Rothschild. This is the common rat flea of tropical countries. Rothschild[377] says: “Although practically cosmopolitan, it cannot apparently flourish in temperate and cold climates.” [377] _Bull. Ent. Res._, 1911, i, pt. 2, p. 92. In the male the bristles of the flap-like process of the clasper all slender; in the female the narrow portion of the receptaculum seminis long. Originally discovered in Egypt. This is apparently the chief plague flea. The Indian Plague Committee have proved that this flea is easily infected when fed on plague rats, and that the bacillus multiplies rapidly in the flea’s stomach and that the fleas may remain infective for fifteen days. How the flea infects man does not apparently seem to have been proved, as it does not do so through its bite, but the excrement is highly infective. It is probable that this poisoned fæcal matter gets to the wound caused by the piercing mouth. *Xenopsylla brasiliensis*, Baker, occurs on rats in West Africa and has been introduced into Brazil. Genus. *Ctenocephalus*, Kolen. Includes the cat and dog fleas. The dog flea, _C. canis_, Dugès, is found on the dog all over the world, but especially in temperate climates. It also occurs on rats. Man is often badly bitten by this insect and it overruns houses. The eggs are laid on rugs, carpets and dust and dirt and amongst dogs’ hair, but are not fastened to it and fall anywhere. The ova may hatch in about fifty hours and the larvæ live for seven days and then spin their cocoons amongst dust and dirt. The pupal stage lasts about eight days. The cat flea (_C. felis_) is widely distributed over the world, and occurs on many mammals beyond the cat, and is also found on rats. Genus. *Hoplopsyllus*, Baker. A genus found in North America related to Pulex, but at once recognized by the prothorax bearing a comb. *Hoplopsyllus anomalus*, Baker, which is found on the ground squirrel (_Citellus beecheyi_) in California, and according to Rothschild once found on the rat, has been proved to carry the plague bacillus and to play an important part in plague infection in California.[378] [378] “Report United States Public Health, 1909,” xxiv, No. 29. Genus. *Ceratophyllus*, Centis. *Ceratophyllus fasciatus*, Bosc. This flea is also found on the rat in Europe and will attack man. It is a plague carrier. It has eighteen to twenty teeth on the prothoracic comb and no black spines on the head. The genus Ceratophyllus of Centis has a pronotal comb and three ante-pygidial chætæ on each side. Two other specimens recorded: _C. londiniensis_, Rothsch., and _C. anisus_, Rothsch. The former on rats and mice in London, the latter on _Felis_ sp. from Japan and _Mus norvegicus_ in California. Genus. *Ctenopsylla*, Kolen. This genus contains a very abundant rat and mouse species, _C. musculi_, Dugès, which is widely distributed over the globe. Genus. *Hystrichopsylla*, Tasch. Large hairy fleas, with no eyes and one or more combs on the abdomen. In the Mediterranean area one species, _H. tripectinata_, Tirah, is common on rats and mice, and also in the Azores. Several others occur on rats and mice. For information concerning these the reader is referred to Rothschild’s papers. *Pulex pallipes* is another species found on the rat and man. *Systematic, Anatomical, and Biological Remarks on Mosquitoes.* Mosquitoes come in the _Nematocera_, one of the sub-orders of the _Diptera_, and are divided into numerous families, of which, however, the _Culicidæ_ are of most interest to us here. Other families as the _Psychodidæ_ and _Chironomidæ_ are also of considerable importance, _vide_ following pages. The head is small, the facetted eyes are placed laterally, but there are no accessory eyes (ocelli). In front of the eyes are situated the comparatively long antennæ, the differences of which strongly mark the distinction of sex.[379] [379] [This is by no means always the case; in the genera Deinocerites, Wyeomyia, Limatus, Theobald, and in Sabethes, Robineau Desvoidy, they are nearly the same in both sexes.--F. V. T.] The antennæ are composed of fifteen or sixteen segments. In the male they are covered with long whorl-like hairs, while in the female the antennal hairs are short--differences that are perceptible even with the naked eye.[380] The proboscis, which is longer than the antennæ, protrudes from the inferior aspect of the head and is composed of the following parts (figs. 387 and 388): Two grooved half tubes, facing one another, of which the upper one is the upper lip (labrum) and the lower one the lower lip (labium), which represents a pair of coalesced maxillæ. Within the tube formed by the labrum and labium are the mandibles and maxillæ, transformed into instruments for piercing, and a single puncturing organ, the hypopharynx. On the right and left, next to the proboscis, are placed the straight five-jointed palpi, the final joint of which is thickened in the male.[381] In biting, the labrum, which is swollen at its free end, is not introduced into the wound like the other mouth parts, but is bent backwards. The labium and hypopharynx push direct into the skin; the maxillæ and mandibles, however, which are needle-like and serrated at the tips, penetrate with a saw-like movement. [The swollen free end of the labrum really means the _labellæ_, two articulated pieces, supposed by some to be the labial palpi. In most species the mandibles are not serrated at their ends.--F. V. T.] The saliva is introduced into the wound through the lumen of the hypopharynx, while the blood is sucked up by the mosquito in the groove of the labium. [380] [This is not always the case, _vide_ previous note.--F. V. T.] [381] [This is only so in Anophelina and in the genus Theobaldinella, Neveu-Lemaire, Grabhamia, Theobald, Acartomyia, Theobald, etc. In true Culex and many other genera the male palpi are pointed.--F. V. T.] The three thoracic segments are soldered together. The central one carries the membranous wings on the sides of the dorsal surface; the posterior somite carries the small halteres (rudimentary posterior wings). There are three pairs of long slender legs on the lower side. [Illustration: FIG. 385.--Head of a male (_a_) and of a female (_b_) Anopheles. Slightly enlarged. (After Giles.)] [Illustration: FIG. 386.--Head of a male (_a_) and of a female (_b_) Culex. (After Giles.)] [Illustration: FIG. 387.--Mouth parts of _Anopheles claviger_.† _h._, hypopharynx; _md._, mandible; _mx._, maxilla; _u.l._, upper lip; _l.l._, lower lip; _p._, palpi. (After Grassi.)] † [This should read _Anopheles maculipennis_, Meig.; there was no type of _A. claviger_.--F. V. T.] [Illustration: FIG. 388.--_Anopheles maculipennis_: transverse section through the proboscis of a female (_a_) and a male (_b_). _hy._, hypopharynx, with duct of the salivary gland; _m._, muscles; _md._, mandibles; _mx._, maxillæ; _l._, labium; _l.l._, labrum. (After Nuttall and Shipley.)] The abdomen has no limbs, is composed of eight (rarely nine) distinct segments; the sexual and anal orifices are at the posterior end, the stigmata on the sides. The intestinal canal (fig. 389) is composed of three principal divisions; the anterior part reaches as far as the front pair of legs, and consists of the œsophagus, which is provided with two small lateral diverticula. [At the commencement of the œsophagus are one or more diverticula, which vary in size; they contain air, food and bacteria.--F. V. T.] The mid gut reaches as far as the fifth and sixth abdominal ring; in front it is thin, and has numerous small supra-œsophageal ganglia; the posterior part is, however, more dilated. Four or five Malpighian tubes, the excretory organs, discharge at the place where the mid gut passes into the terminal gut. The pair of salivary glands have one common excretory duct leading into the hypopharynx. [Illustration: FIG. 389.--Longitudinal section of an Anopheles, showing alimentary canal. In the forepart of the thorax is the salivary gland consisting of three tubules; ventrally, the suctorial stomach extending into the abdominal cavity; the stomach, and at the posterior end of the abdomen the Malpighian vessels. (After Grassi.)] These glandular bodies are situated in the thorax; each consists of three slightly serpentine tubules, the dorsal and ventral tubes being long, the central one shorter. The above-named characteristics apply to both genera Culex and Anopheles, but in the genus Culex is smaller, Anopheles larger. [In Anopheles the ends of the ducts in the lobules are dilated, whilst in most of the genera the ducts are the same size all along. The lobules may bifurcate, and in Psorophora there are five lobules.--F. V. T.] The legs of the genus Culex are about the same length as the whole body; in Anopheles they are double that length.[382] In Anopheles the palpi and proboscis are of equal length; in Culex the condition is different, according to sex. In the male the palpi are longer than the proboscis; in the female considerably shorter and the number of segments diminished. The venation of the wings exhibits further points of differentiation, as also their adornment, though this last sign is not by any means always conclusive; most species of the genus Culex have unspotted wings, whilst those of Anopheles are usually spotted. More important is the fact that in Culex the abdomen is decorated with small scales, similar to those on butterflies, whereas there are small bristles on the abdomen of Anopheles. [This cannot be said to be a character by which an Anopheline may be told from a Culicine, for in such common Anopheline genera as Cellia and Neocellia we get plenty of scales on the abdomen.--F. V. T.] An experienced observer can, however, separate the two genera by the difference in size and their manner of resting. When settled they either touch the resting place with all the legs or only with the four anterior legs. In consequence of the different length of the legs, the body of Culex approaches the resting place more closely; moreover, Culex holds the abdomen parallel or at an acute angle to the resting surface, whereas Anopheles carries the abdomen directed upwards (at an angle of about 145°) and holds the head down. Both genera, however, usually only rest on the four anterior legs, and then, as has long been known, Culex carries the third pair directed towards the dorsum, while those of Anopheles hang down. [382] [This is certainly not always the case.--F. V. T.] In regard to the differentiation of the species, I must refer you to the special literature, and content myself by observing that about 150 species of Culex and about fifty species of Anopheles have been described, of which fifty about four are found in Europe. [The number of known Anophelines now is more--100 species--of other Culicidæ over 700.--F. V. T.] According to our present knowledge it appears that the entire genus Anopheles can transmit malaria to man; this observation has been confirmed in _Anopheles claviger_, Fabr.; _A. maculipennis_, Meig.; _A. bifurcatus_, L.; _A. superpictus_, Grassi; _A. pseudopictus_, Gr., all of which are found in Italy,[383] Germany, etc., as well as in the tropics. Moreover, in _A. costalis_, Loew; _A. funestus_, Giles (Africa); _A. quadrimaculatus_, Say (North America), and _A. rossii_, Giles; the latter is perhaps identical with _A. superpictus_, Gr., as well as with _A. culicifacies_ (India). [_Anopheles maculipennis_ and _A. claviger_ are the same. Certainly neither _maculipennis_ nor _bifurcatus_ has been found in the tropics. _Anopheles quadrimaculatus_, Say, is the same as _A. maculipennis_. There is no evidence that _all_ Anophelines carry malaria, but there is much to show that certain species only are capable of so doing. A list of known carriers is given later.--F. V. T.] [383] Compare Ficalbi, E., “Venti spec. di zanzare (_Culicidæ_) ital...,” _Bull. Soc. ent. ital._, 1899, xxxi; abstracted in _Centralbl. f. Bakt., Par. u. Infektionsk._, 1900, xxviii, p. 397. [Illustration: FIG. 390.--_Anopheles maculipennis_, Meigen. Enlarged. (After Grassi.)] Everyone is aware that mosquitoes swarm at sunset in fine weather, and then seek out human beings and other warm-blooded animals to take food. In this regard, however, the sexes differ, for it is almost without exception that the females only suck blood, while the males subsist on the juices of plants (blossoms or fruits).[384] After sucking, and when night has fallen, the mosquitoes find a place of refuge, for which purpose they utilize the grasses or foliage of trees and bushes, or inhabited or uninhabited rooms of houses, also cellars, stables, verandahs, etc., where they also pass the day. [384] Both males and females may be kept alive in captivity for a long time if given fruits, or even only sugar and water. [Some mosquitoes bite in the daytime--Stegoymia and some Anophelines; some bite right into the night, as _Culex fatigans_ and _C. pipiens_.--F. V. T.] The period required for digestion varies according to the temperature. It takes two days in summer, and may take up to ten days or more in cool weather. After digestion is complete more food is taken up, this being necessary [in some species only--F. V. T.] for the maturing of the sexual products in the female. [Illustration: FIG. 391.--Larva of _Anopheles maculipennis_, Fabr. Enlarged. (After Grassi.)] [Illustration: FIG. 392.--Larva of Culex. Enlarged. (After Grassi.)] It is still unknown under what circumstances copulation takes place;[385] in any case, sooner or later the females are fecundated, and when the ova have become mature, and the season is not too far advanced, they seek a suitable place in which to deposit them.[386] These are larger or smaller, permanent or temporary, collections of standing water, pools, puddles, lakes, pits, water in rain-water barrels, basins, etc. Nevertheless, certain kinds prefer certain waters; thus _Anopheles_ (_claviger_) _maculipennis_ and several of the Culices seek stagnant water overgrown with swamp vegetation and decomposing vegetable matter; _A. bifurcatus_ and certain Culices, clear water with some vegetation (such as fountains and the lakes in gardens and parks); _Culex pipiens_ has a preference for rain-water barrels, even though the water be dirty and evil-smelling. [I have found the larvæ of _Anopheles bifurcatus_ living in great numbers in ponds and lakes completely overgrown with floating water-weeds, and those of _Culex pipiens_ in liquid manure. [385] The act of copulation in many species is now known. The female Culex has three receptaculæ seminalis, while the female Anopheles has one receptaculum seminis. [386] It is certain that the females perish immediately after depositing the ova; but this does not always hold good, as a part of them survive for a few days. The males die soon after copulation. _Sexual Organs of the Mosquito._--The female has a pair of ovaries, opening into a single tube by the ovarian tubes; into the single tube opens a duct coming from the spermathecæ, and also a mucous gland. The spermathecæ store up the male cells. The male organs consist of two testes joined by ducts (vasa deferentia) to the ejaculatory duct formed by their union. Each vas deferens is joined by a short tube with the sac-like vesicula seminalis.--F. V. T.] There is also a difference in the manner in which Culex and Anopheles deposit their ova. Culex deposits two to three hundred eggs in compact heaps that float on the water, and in which the eggs stand perpendicularly one next the other; whereas _Anopheles maculipennis_ deposits only three or four up to twenty eggs, united in groups that float horizontally on the water; the eggs of _A. bifurcatus_, again, are arranged in star-like groups. The eggs are about 0·75 mm. in length, and assume a dark hue soon after being laid. The development only occupies a few days. The young larvæ grow rapidly, changing their integument several times; the larvæ also differ in the various genera, though they have a general resemblance (figs. 391 and 392). The long legless larva has a flattened head, a fairly broad, rectangular, or trapeziform thorax, on which there are bristles, and an abdomen distinctly segmented, and on the segments of which there are also lateral bristles. The situation of the stigmata marks the difference between the two genera. Though in both genera the stigmata are at the posterior end and on the dorsal surface, they are in Anopheles close to the surface of the body; in Culex, however, they are on the free end of a long tube (siphon). [Illustration: FIG. 393.--Pupa of _Anopheles maculipennis_, Meig. Enlarged. (After Grassi.)] The position of the larva in the water also differs. The larva of Anopheles lies almost horizontally beneath the surface of the water, the posterior border of the penultimate abdominal segment, upon which the stigmata are situated, being on the surface; whereas the larva of Culex hangs head downwards perpendicularly in the water, the point of the siphon only touching the surface. In about a fortnight the larva is fully grown and becomes a pupa. The pupa (fig. 393), which moves in jerky movements, remains in the water, but partakes of no food. In shape it somewhat resembles a tadpole, that is to say, it consists of a bulky anterior portion, on the surface of which the head, with its appendages, is recognizable, and a more slender segmented abdomen. Above, on the thorax, there are two small trumpet-shaped breathing tubes for the conveyance of air to the tracheal system. After three or four days the perfect mosquito hatches out, remains a short time on the surface of the water until its chitinous integument is hardened, and then flies away. The females that are fertilized in the autumn hibernate in sheltered spots in the open air, or in houses, cellars, under stairs, in stables, barns, etc., and are the progenitors of the first generation of the following year. In accordance with the climate of a country, or the kind of weather of a year, the conditions in regard to the manner of life and the duration of the development of the mosquito vary. At all events, the life-history of the mosquito elucidates many points relating to malaria which were hitherto not understood. [The length of the egg, larval and pupal life varies so much that it is not possible to give an account of any value here. Frequently the eggs may incubate in two days, whilst I have had _Stegomyia fasciata_ eggs from Cuba that have hatched out under abnormal circumstances more than two months after they were laid (“Mono. Culicid.,” iii, p. 6). Some larvæ, as _Anopheles bifurcatus_, live for months during the winter. Some mosquitoes therefore hibernate as larvæ. The larvæ and pupæ of the different genera present very marked characters, mainly in regard to the structure of the siphons. Specific differences may be found in the frontal hairs of Anopheline larvæ and in the number and arrangement of a group of spines at the base of the siphon in Culicines.--F. V. T.] *Culicidæ or Mosquitoes.* The importance of these insects to man is very great. They not only produce painful bites, which may become inflamed and give rise to a considerable amount of œdema, but they are more important on account of the part they play in the distribution of various diseases. _Culicidæ_ may not only carry disease germs, but act as intermediate hosts for certain parasites, such as some of the _Anophelina_ for malarial parasites, Culex for Filariæ, and Stegomyia for yellow fever, etc.; the last-named is in any case the distributor of that fatal disease. It is therefore very necessary to know the life-history, habits and characters of these pests. Mosquitoes exist in almost all parts of the world from the Arctic circle to the tropics; temperate regions suffer from them less than the two extremes, but even there they form not only a source of great annoyance but of danger as malaria and possibly now and again yellow fever carriers. A few years ago comparatively few species were known, now some 800 odd have been described. Their number will probably not stop far short of 1,000, in spite of the fact that many have been described under different names, yet really the same species. Some are purely domestic, others entirely sylvan; the former, as we might expect, often have a very wide distribution, having been taken from place to place in boats and trains. The more rapid transport becomes, the greater becomes the possibility of this wide distribution of many species increasing, and the spread of other species from their natural home to foreign parts by sea and then by trains further inland. [Illustration: FIG. 394.--Heads of Culex and Anopheles: (1) Culex male; (2) Culex female; (3) Anopheles male; (4) Anopheles female. (After Daniels.)] All _Culicidæ_ are aquatic in their larval and pupal stages. Almost all small collections of water, both natural and artificial, may form breeding grounds for these pests. Some even breed in pitcher plants and many in bromelias. The favourite resorts for the larvæ of Anophelina are small natural collections of water, such as puddles, ditches and small pools around swamps; certain species (_A. maculipennis_, etc.) live in rain barrels as well. They may also occur in the sluggish water at the edges of rivers or even in mid river, where the flow is checked by masses of water weeds (_Myzomyia funesta_, etc.). The Stegomyias prefer artificial collections of water, but also occur in natural pools. The yellow fever species (_S. fasciata_) prefers small collections, such as in barrels, pots, jars, etc. Culex occur in all manner of places--rain barrels, tanks, cisterns, ponds and ditches. Some of the South American species of Culex, Wyeomyia, Joblotia, etc., breed in the collections of water at the base of bromelia leaves.[387] Very few Culicid larvæ live in salt water except in Australia, where Dr. Bancroft has found them in salt water of specific gravity 1·040 (_Mucidus alternans_ and _Culex annulirostris_). Other salt water mosquitoes are known in America. The food of the larvæ is very varied; the majority appear to feed upon confervæ, small crustacea and insects; some are cannibals, readily devouring others of their own kind. The larger larvæ of Megarhinus, Psorophora, Toxorhynchites and Mucidus are extremely ravenous and devour one another. [387] “Wald Mosquitoes und Wald Malaria,” Dr. Lutz, _Centralbl. f. Bakt., Par., u. Infektionsk._, i Abt. Orig., xxxiii, No. 4. [Illustration: FIG. 395.--_a_, eggs of Culex; _b_^1 _b_^2, eggs of Anopheles; _c_, egg of Stegomyia; _d_, egg of Tæniorhynchus; _e_, egg of Psorophora.] There are two main types of larvæ, the Anopheline and Culicine; in the former there is no respiratory siphon, in the latter the siphon is long or moderately long. The head offers certain marked peculiarities which are of specific value; this especially applies to the _Anophelina_, in which the frontal hairs are of great service in distinguishing the larvæ,[388] whilst in Culex the number and position of the spines at the base of and on the siphon are characteristic. The position assumed by the larvæ in the water also varies in the different groups; most of the Anophelines lie horizontally, most of the _Culicina_ and _Ædeomyina_ hang head downwards. The pupæ also vary, but not to the same extent; the chief differences to be noticed are in the form of the two respiratory trumpets. [388] Information sent me by Dr. Grabham shows this statement to be not quite correct, as the frontal hairs may vary in different stages of the same larva. This he has shown in _Cellia albipes_, Theob., and I have noticed it in a Nyssorhynchus from Africa. [Illustration: FIG. 396.--Diagram showing the structure of a typical mosquito. (Theobald.)] The eggs, which may be laid separately (_Anopheles maculipennis_, _Stegomyia fasciata_, _Joblotia nivipes_, etc.), or in rafts (_Culex pipiens_, _C. fatigans_) or in chains (_Pseudotæniorhynchus fasciolatus_), present a great variety of forms. The most peculiar are shown in fig. 395 (Tæniorhynchus, Culex, Stegomyia, Anopheles, Psorophora). As in all insects, they differ very materially in each species of one genus. Those best known are the Anopheline eggs. The eggs always float on the surface of the water; immersion soon destroys them, but many may occur in mud and can resist desiccation. [Illustration: FIG. 397.--Types of scales, _a_ to _k_; head and scutellar ornamentation, 1 to 5; forms of clypeus, 6. (Theobald.) 1, head and scutellum of Stegomyia, etc.; 2, of Culex and Mansonia; 3, of Howardina, Ædes, etc.; 4, of Megarhinus and Toxorhynchites, etc.; 5, of Cellia and some other Anophelines; 6, _a_′, clypeus of Culex; _b_′ of Stegomyia; _c_′, of Joblotia.] _Characters of Adult Culicidæ._--The chief characters by which true mosquitoes, or _Culicidæ,_ are known are the following:-- (1) Wings always with the veins covered with scales; the longitudinal veins, usually six in number (in one genus seven); the costal vein carried round the border of the wing. (2) Head, thorax and abdomen usually, but not always (Anopheles, etc.), covered with scales. (3) Mouth parts formed into a long piercing proboscis. As a rule the males may be told from the females by their antennæ being plumose, whilst in the females they are pilose (_vide_ fig. 394), but this does not invariably hold good, for in Deinocerites, Theobald, and Sabethes, Desvoidy, and others, they are pilose in both sexes. The labial palpi are very variable in regard to their form and the number of segments; in the _Anophelina_ they are long in both sexes, as long or nearly so as the proboscis, more or less clubbed in the males; in _Culicina_, _Joblotina_ and _Heptaphlebomyia_, they are long in the males, short in the females; in _Ædeomyina_, short in both sexes. [Illustration: FIG. 398.--Neuration of Wing. _Explanation of Wing, Veins and Cells._--A, costal cell; B, sub-costal cell; C, marginal cell; D, first sub-marginal cell (= first fork cell); E, second sub-marginal cell; F, first posterior cell; G, second posterior cell (= second fork cell); H, first basal cell; I, second basal cell; J, third posterior cell; K, anal cell; L, auxiliary cell; M, spurious cell; _c_, costal vein; 1_st_--6_th_, first to sixth longitudinal veins; _a_, _a_′ and _a_′′, incrassations (_a_′ called by Austen the sixth vein, _a_′′ the eighth vein); y, supernumerary cross vein; z, mid cross vein; _p_, posterior cross vein; _s.c._, sub-costal. (Theobald.)] _Scales_.--The most important structural peculiarities in _Culicidæ_ are the scales, which form the chief and most readily observed characters for separating genera and species. The importance of scale structure has been recently ignored by some workers, who are probably right academically, but as a means of separating groups, and so more easily running down a species, the practical man is strongly advised to follow this method. As to what a genus is, is purely a matter of personal opinion. If one examines any recent standard work on entomology one will find a species being placed in varied genera by the varied authorities. The head, thorax, abdomen and wings are in nearly all cases clothed with squamæ of varied form, of which the following are the main types (fig. 397):-- (1) Flat, spade-shaped scales (_a_). (2) Narrow curved scales (_e_). (3) Hair-like curved scales (_d_). (4) Spindle-shaped scales (_f_). (5) Small spindle-shaped scales (_g_). (6) Upright forked scales (_h_) and (_i_). (7) Twisted upright scales (_j_). (8) Inflated or pyriform scales (_k_). (9) Mansonia scales (_b_). (10) Small broad asymmetrical scales (_c_). Various other varieties are found on the wings, such as:-- (1) Narrow linear lateral scales. (2) Narrow lanceolate scales. (3) Broad lanceolate scales. (4) Elongated, broad, truncated scales (= Pseudotæniorhynchus-like scales). (5) Pyriform scales. (6) Asymmetrical broad or Tæniorhynchus scales. (7) Flat spade-like scales.[389] [389] Heart-shaped scales occur on the wings of Etiorleptiomyia. The wings have a series of scales along the middle line of the veins, and also lateral scales to all or nearly all the veins. The wing is also fringed by a series of scales (fig. 396), which, however, are of little systematic importance; the so-called “border scales” (b.s.) vary, however, to some extent, and are useful characters in separating some of the Tæniorhynchus. THE CLASSIFICATION OF _Culicidæ_. SECTION A.--Proboscis formed for piercing; metanotum nude. Scutellum simple. I. Wings with six-scaled longitudinal veins. A. Palpi long in the male. α. Palpi long in both sexes, clavate in ♂ _Anophelina_. I. First submarginal cell as long or longer than the second posterior cell. Antennal segments without dense lateral scale tufts. { {Wing scales { { lanceolate _Anopheles_, Meigen. { {Wing scales { { mostly long { { and narrow _Myzomyia_, Blanchard. {Prothoracic {Wing scales { lobes { as above, { simple; no { but fourth { flat head { long vein Thorax and { scales { near base abdomen { { of third and _Neomyzomyia_, Theobald. with hair- { { outstanding like scales{ { scales on { { prothoracic { { lobe { {Wing scales { { partly large { { and inflated _Cycloleppteron_, Theobald. { Prothoracic lobes mammil- { lated; some flat head { scales. Basal lobe of ♂ { genitalia of two segments _Stethomyia_, Theobald. Prothoracic lobes with dense outstanding scales _Feltinella_, Theobald. Thorax with some narrow curved scales; abdomen hairy _Pyretophorus_, Blanchard. Wing scales small and lanceolate. Wing scales broad and lanceolate _Myzorhynchella_, Theobald. Thorax with hair-like curved scales, some narrow curved ones in front; abdomen with apical lateral scale tufts, scaly venter; no ventral tuft _Arribalzagia_, Theobald. Thorax with hair-like curved scales; abdominal scales on venter only, with a distinct ventral apical tuft _Myzorhynchus_, Blanchard. Much as above, but abdomen with long spine-like dense lateral tufts _Chrystia_, Theobald. Thorax with very long hair-like curved scales; abdomen pilose, except last two segments which are scaly; dense scale tufts on third femora; wings with broadish, blunt, lanceolate scales _Lophoscelomyia_, Theobald. {Abdominal scales as { lateral dorsal patches { of small flat scales; Thorax and { thoracic scales narrow abdomen { and curved, or spindle- { shaped _Nyssorhynchus_, Blanchard. with scales {Abdomen nearly completely { covered with irregular { scales and with lateral _Cellia_, Theobald. { tufts {No lateral scale tufts _Neocellia_, Theobald. Thoracic scales hair-like except a few narrow curved ones in front; abdominal scales long, broad and irregular _Kerteszia_, Theobald. Thorax with hair-like curved scales and some broad straight scales, others spatulate on sides. Abdomen covered with fine hairs except last three segments, which are scaly. Tufts of scales on hind femora. Wing scales lanceolate _Manguinhosia_, Cruz. Antennal segments with many dense scaly tufts _Chagasia_, Cruz. Antennæ with outstanding scales on second segment, more appressed ones on the first. At least one segment of abdomen with long flat more or less spatulate scales _Calvertina_, Ludlow. II. First submarginal cell very small _Bironella_, Theobald. With a distinct cylindrical tubercle projecting obliquely from the prothoracic region _Dactylomyia_, Newstead and Carter.[390] Scutellum trilobed. First submarginal cell much smaller than the second posterior cell; proboscis long and bent _Megarhininæ._ Palpi long in both sexes _Megarhinus_, Rob. Desvoidy. Last segment of ♂ palpi blunt. Last segment of ♂ palpi long and pointed _Ankylorhynchus_, Lutz. [390] The following genera of Anophelites have been founded by James†:-- † _Records of Indian Museum_, 1910, iv, No. 5, p. 98. (1) Abdomen with hairs but no scales. Thorax with dorsum with long narrow curved scales, which form on the anterior promontory a thick bunch projecting over the neck. Prothoracic lobes with a tuft of rather broad true scales, upright forked scales of head of usual broad expanding type: Patagiamyia, James. Includes Gigas, Giles, and Lindesayi, Giles. Both seem to me typical Anopheles. (2) Abdomen as above; Thorax very similar. Prothoracic lobes with hairs, no scales. Upright forked scales of head rod-shaped: Neostethopheles, James. Includes Atkenii, James; Immaculatus, Theobald; Culiciformis, James and Liston. These seem to me to be true Anopheles. (3) Abdomen with hairs and scales on dorsum of each segment; ventrally there are six scaly tufts on the apices of six segments. Thorax with scales and a tuft of outstanding ones on prothoracic lobes: Christophersia, James. Type Halli, James. Very close to if not identical with Cellia. (4) Head with narrow curved scales lying rather flat upon head and flat lateral scales, upright forked ones behind. Central lobe of scutellum with tuft of narrow curved scales, lateral lobes with large flat oval scales; male palpi longer than proboscis, two large apical segments with long projecting hairs: Leslieomyia, Christophers. Type _Leslieomyia tæniorhynchoides_, Christophers, from Amritsar, India. (5) Abdomen with first six or seven segments with hairs only, eighth and seventh (?) with scales, also genital processes. Thorax with hairs and narrow curved scales sharp pointed, blunt-ended broad scales on each side of anterior third. No tufts of scales on prothoracic lobes. Head usual type of upright forked scales: Nyssomyzomyia, James. Type Rossii, Giles. β. Palpi short in the female _Toxorhynchites_, Theobald. First submarginal cell longer than the second posterior cell _Culicinæ._ Legs more or less densely scaly; head not entirely clothed with flat scales; all the legs densely scaly. Wings with large pyriform scales _Janthinosoma_, Arribalzaga. Head entirely clothed with flat scales. Legs uniformly scaled with flat scales. Head and scutellar scales all flat and broad. Palpi of ♀ short, of ♂ thickened apically and tufted _Stegomyia_, Theobald. Palpi of ♀ longer than in Stegomyia and in ♂ long and thin, acuminate, simple _Desvoidea_, Blanchard. Head scales mostly flat, but a median line of narrow curved ones; scutellar scales flat on mid lobe, narrow curved on lateral lobes and palpi longer than proboscis _Macleayia_, Theobald. Head scales mostly flat, irregular, narrow curved ones behind; mid lobe scutellum with flat scales, lateral with narrow curved; ♂ palpi shorter than proboscis _Catageiomyia_, Theobald. Head scales mostly flat, but a few narrow curved ones in middle in front; scutellar scales all flat _Scutomyia_, Theobald. Head scales all flat; scutellar scales all narrow curved _Skusea_, Theobald. Head with flat scales, except a small median area of narrow curved ones; scutellar scales all narrow curved _Howardina_, Theobald. Head with all flat scales except a thin line of narrow curved ones behind; scutellar scales all narrow curved _Danielsia_, Theobald. Head with small flat scales over most of surface, with median line and line around eyes of narrow curved ones; scutellar scales bluntly spindle or club-shaped _Hulecoetomyia_, Theobald. Head and scutellar scales narrow curved. Wing scales long, narrowly lanceolate, collected in spots; palpi clubbed in ♂; five-jointed and rather long in ♀ _Theobaldia_, Neveu-Lemaire. Wing scales (lateral) long and narrow, and ♀ palpi three-jointed, ♂ not clubbed and hairy _Culex_, Linnæus. Wing scales at apex of veins dense and rather broad, femora swollen; small dark species _Melanoconion_, Theobald. Wings with short, thick, median scales and short, broadish lateral ones on some of the veins; scales mottled; fork-cells rather short _Grabhamia_, Theobald. Wings with dense, broadish, elongated, truncated scales _Pseudotæniorhynchus_, Theobald. Wings with broad, short, asymmetrical scales _Tæniorhynchus_, Arribalzaga. Head covered with rather broad, flat, spindle-shaped scales; scutellum with small flat scales to mid lobe _Gilesia_, Theobald. Head clothed with flat, irregularly disposed scales all over, with patches of narrow curved ones; ♂ palpi clubbed _Acartomyia_, Theobald. Abdomen with projecting flat lateral scales with deeply dentate apices; wings not ornamented _Lasioconops_, Theobald. Wings ornamented; scutellum with flat and narrow curved scales _Finlaya_, Theobald. γ. Palpi short in ♂ and ♀ _Ædeomyina._ Wings unornamented. Antennæ pilose in ♂ and ♀; second joint very long _Deinocerites_, Theobald. Antennæ plumose in the ♂. Head clothed with narrow curved and flat scales. Mid-lobe of scutellum with six border- bristles. Scutellum with narrow curved scales. Palpi in ♀ four-jointed, in ♂ two- jointed _Ædes_, Meigen. Mid-lobe of scutellum with four border bristles. Scutellum with flat scales. Head clothed with flat scales only. Fork-cells normal length. Mid-lobe of scutellum with four border- bristles. Palpi of ♀ two-jointed _Verallina_, Theobald. Palpi of ♀ five-jointed, metallic _Hæmagogus_, Williston. Fork cells very small or small. Scutellar scales flat. First submarginal cell longer than the second posterior cell; no flat scales on mesothorax _Ficalbia_, Theobald. First submarginal cell smaller than the second posterior cell; flat scales on mesothorax _Uranotænia_, Arribalzaga. Scutellar scales narrow curved. First submarginal cell as in Uranotænia _Mimomyia_, Theobald. Wings ornamented with Mansonia-like scales _Ædeomyia_, Theobald. SECTION B.--Metanotum ornamented with chætæ, squamæ or both. α. With chætæ only. Proboscis longer than whole body; lateral wing scales Tæniorhynchus-like _Phoniomyia_, Theobald. Proboscis as long as whole body in ♀ } frons drawn out into a prominence; } _Binotia_, Blanchard = wing scales rather broad and long } _Runchiomyia_, Theobald. Proboscis not as long as the whole body; lateral vein scales narrow _Wyeomyia_, Theobald. Proboscis not as long as whole body, swollen apically; wing scales long and broad _Dendriomyia_, Theobald. β. Metanotum with squamæ and chætæ. Palpi short in ♂ and ♀. Proboscis straight in ♀ and ♂; legs with scaly paddles _Sabethes_, Rob. Desvoidy. Venation like Sabethes. Legs simple _Sabethoides_, Theobald. Venation like Culex _Goeldia_, Theobald. Proboscis in ♂ elbowed, with two scaly tufts _Limatus_, Theobald. Palpi long in ♂, short in ♀ _Joblotina_, Blanchard. II. Wings with seven-scaled longitudinal veins: Culex type _Heptaphlebomyia_, Theobald. SECTION C.--Proboscis short, not formed for piercing _Corethrina._ Metatarsus longer than first tarsal joint _Corethra_, Linnæus. Metatarsus shorter than first tarsal joint _Mochlonyx_, Ruthe.[391] [391] Many other genera have been created; these will be found in my catalogue of _Culicidæ_ in my “Monograph of the Mosquitoes of the World,” 1901–10, 5 vols., in my “Novæ Culicidæ,” family _Culicidæ_, Genera Insectorum, etc. NOTES ON THE DIFFERENT GENERA. Sub-family. *Anophelina.* The following Anophelines have been recorded as malaria carriers:-- *_Anopheles maculipennis_, Meigen. _Anopheles bifurcatus_, Linnæus. *_Myzomyia funesta_, Giles. _Myzomyia lutzii_, Theobald. *_Myzomyia rossii_, Giles. _Myzomyia listonii_, Liston. _Myzomyia culicifacies_, Giles. _Pyretophorus superpictus_, Grassi. *_Pyretophorus costalis_, Loew. _Pyretophorus chaudoyei_, Theobald. *_Cellia argyrotarsis_, Robineau Desvoidy. _Myzorhynchus pseudopictus_, Grassi. _Myzorhynchus barbirostris_, Van der Wulp. _Myzorhynchus sinensis_, Wiedemann. _Myzorhynchus paludis_, Theobald. _Myzorhynchus mauritianus_, Grandpré. _Neocellia stephensii_, Liston. _Neocellia willmori_, James. _Nyssorhynchus theobaldii_, Giles. _Nyssorhynchus fuliginosus_, Giles. _Nyssorhynchus annulipes_, Walker. Those marked with an asterisk (*) also carry the larvæ of _Filaria bancrofti_, as also do _Myzorhynchus minutus_, Theobald, and _Myzorhynchus nigerrimus_, Giles. Genus. *Anopheles*, Meigen. “Syst. Beschr. Europ. zwei. Ins. I,” 1818, ii, p. 2, Meigen; “Mono. Culicid.,” 1903, i, p. 191; iii, p. 17; and 1910, v, p. 3, Theobald. This genus contains a few large species found either in temperate climates or in hills and mountains of warm climates. The type is the European and North American _A. maculipennis_. [Illustration: FIG. 399.--Wing of _Anopheles maculipennis_, Meigen.] _A. maculipennis_, Meigen. This species and _A. bifurcatus_ are malaria carriers. True Anopheles only occur in Europe, North America, the North of Africa and in the mountains of India, and one has been found by Bancroft similar to _A. bifurcatus_ in Queensland. They are easily told by the absence of scales on thorax and abdomen, and by the rather densely scaled wings with lanceolate scales. Genus. *Myzomyia*, Blanchard; *Grassia*, Theobald. _Comp. rend. heb. Soc. Biol._, No. 23, p. 795, Blanchard; “Mono. Culicid.,” 1910, iii, p. 24; v, p. 16, Theobald. This genus occurs in Asia, Africa and South America, Europe and East Indies. The type is _M. funesta_, Giles, found in Central and West Africa. Although structurally there is not much difference between this genus and Anopheles, they differ greatly in appearance, and there are usually a few narrow curved thoracic scales projecting over the head, whilst the wing scales are much smaller in proportion, and the wings more uniformly spotted, always so along the costa. _Funesta_ and _lutzii_ are undoubtedly malaria bearers and also _rossii_. Genus. *Neomyzomyia*, Theobald. “Mono. Culicid.,” 1910, v, p. 29. A single species only occurs in this genus, _N. elegans_, James, from India. In this genus, which is near to Myzomyia, the fourth long vein is very near the base of the third, and there are outstanding scales on the prothoracic lobes, and there is a marked tuft of dense scales at the posterior angles of the head. Genus. *Cycloleppteron*, Theobald. “Mono. Culicid.,” 1903, ii, p. 312; 1903, iii, p. 58; 1910, v, p. 33. Two common species only occur in this genus, _C. grabhamii_, Theob., from Jamaica, and _C. mediopunctatus_, Theob. (Lutz., ms.), from South America. The chief character is the presence of large black inflated pyriform scales on the wings. The palpi are densely scaled. Neither have been shown to be malaria bearers. Genus. *Feltinella*, Theobald. “Mono. Culicid.,” 1907, iv, p. 56. A single species, so far only found in this genus. The basal lobes of the male genitalia of two segments, the prothoracic lobes with dense outstanding scales. The species, _F. pallidopalpi_, Theob., occurs in Sierra Leone. Genus. *Stethomyia*, Theobald. “Mono. Culicid.,” 1903, iii, p. 13; 1907, iv, p. 59; 1910, v, p. 35. Four species occur in this marked genus--one _S. nimba_, Theob., from British Guiana and Para, another _S. fragalis_, Theob., from the Malay States, _S. culiciformis_, James and Liston, from India, and _S. pallida_, Ludlow, from India. The former may be a malaria carrier, for Dr. Low says: “Malarial fever is got amongst the Indians and often of a severe type. In that connection it is interesting that in the interior, at a place called Corato, I got an entirely new Anopheles in large numbers.” The genus is easily told by its unornamented wings, flat head scales, mammillated prothoracic lobes and long thin legs. Genus. *Pyretophorus*, Blanchard; *Howardia*, Theobald. _Compt. rend. heb. Soc. Biol._, No. 23, p. 705, Blanchard; _Journ. Trop. Med._, v, p. 181; and “Mono. Culicid.,” 1903, iii, p. 13; 1910, v, p. 36, Theobald. Forty-four species come in this genus, of which _Anopheles costalis_, Loew, is the type. This genus is found in Africa, India, Europe and in Australia. Three species are proved malaria bearers, namely, _P. costalis_, Loew, _P. chaudoyei_, Theob., and _P. superpictus_, Grassi. Members of this genus can be told by having narrow curved thoracic scales, hairy abdomen, and much-spotted wings. Genus. *Myzorhynchella*, Theobald. “Mono. Culicid.,” 1907, iv, p. 78. In this genus the thorax has distinct, narrow curved scales, and the abdomen is hairy, the wing scales broad and lanceolate, and the head with broad scales not closely appressed, but not forked or fimbriated. Five species are known: _lutzi_, Cruz; _parva_, Chagas; _nigritarsis_, Chagas; _tibiomaculata_, Neiva; _gilesi_, Neiva; and _nigra_, Theobald. They are all recorded from Brazil, and _nigra_ also from Mexico. Genus. *Manguinhosia*, Cruz, in Peryassu. “Os Culicideos do Brazil,” 1908, p. 112. A single marked species from the Brazils. The thorax has piliform curved scales, and some narrow curved and flattened ones on the sides. Abdomen pilose, except the last three segments which are scaled. No tufts of scales on posterior femora. Allied to Lophoscelomyia, but at once told by the absence of scale tufts on the hind femora. _M. lutzi_, Cruz, Brazil. Genus. *Chrystya*, Theobald. “Rep. Sleeping Sickness, Roy. Soc. Eng.,” 1903, vii, p. 34. A very marked genus in which the hairy abdomen has very long, dense, hair-like, apical, scaly tufts to the segments. A single species only so far known, _C. implexa_, Theobald, from Africa (Uganda, Sudan, etc.). Genus. *Lophoscelomyia*, Theobald. _Entomologist_, 1904, xxxvi, p. 12. A single species only, from the Federated Malay States. The hind femora have dense, apical scale tufts; the thorax long, hair-like curved scales; abdomen pilose, except the last two segments which are scaly; wings with broad, blunt, lanceolate scales. Genus. *Arribalzagia*, Theobald. “Mono. Culicid.,” 1903, iii, pp. 13 and 81; and 1910, v, p. 48. Two species only occur, found in South America. The thorax and abdomen have scales and hairs respectively, as in Pyretophorus, but the abdomen has in addition prominent lateral apical scale tufts to the segments and a scaly venter. Wings with membrane tinged in patches and wing scales bluntly lanceolate and very dense. The type is _A. maculipes_, Theob. found in Trinidad and Brazil; _A. pseudomaculipes_, Cruz, also in Brazil. Genus. *Myzorhynchus*, Blanchard; *Rossia*, Theobald. _Compt. rend. heb. Soc. Biol._, 1902, No. 23, p. 795, Blanchard; _Journ. Trop. Med._, 1902, p. 181, Theobald; “Mono. Culicid.,” 1903, iii, p. 84; 1907, iv, p. 80; 1910, v, p. 49. A very marked genus of large, dark, densely scaled species, found in Europe, Asia, Africa and Australia. The thorax with hair-like curved scales; the abdomen with ventral and apical scales, and a median ventral apical tuft, and with very densely scaled palpi in the female, and densely scaled proboscis. It seems to be mainly an Asiatic and East Indian genus, but three species occur in Africa and one in Australia. They are mostly sylvan species and bite severely. Fourteen species are known. Five are malaria carriers (_vide_ list, p. 566). Genus. *Nyssorhynchus*, Blanchard; *Laverania*, Theobald. “Mono. Culicid.,” 1910, iii, p. 14; v, p. 55, Theobald; _Compt. rend. heb. Soc. Biol._, No. 23, p. 795, Blanchard. A group of small, closely allied species found in Asia, Africa and Australia, twelve out of the twenty species coming from India. The thorax is covered with narrow curved and spindle-shaped scales, abdomen with small, flat or narrow curved dorsal scales, especially on the apical segments or in patches; the legs are always banded or spotted with white, and the tarsi have as a rule one or more pure white segments. (This banding and spotting is of no generic value, however.) The species show considerable seasonal variation. The type of the genus is _N. maculatus_, Theobald. Three are malaria carriers (_vide_ list, p. 566). Genus. *Cellia*, Theobald. “Mono. Culicid.,” 1903, iii, p. 107; 1910, v, p. 67. Very marked Anophelines, with densely scaly abdomens, the scales irregularly disposed on the dorsum and forming dense lateral tufts; thorax with flat spindle-shaped scales; palpi densely scaled and also the wings. The type of the genus is the African _C. pharoensis_, Theob. It is represented in Asia by _C. kochii_, Dönitz; in West Indies and South America by _C. argyrotarsis_, Desvoidy, and _C. bigotii_, Theob.; in Africa by _C. squamosa_, Theob., etc. _C. argyrotarsis_, Desvoidy, and _C. albimana_, Wiedemann, are undoubtedly malaria bearers. Genus. *Neocellia*, Theobald. “Mono. Culicid.,” 1907, iv, p. 111. Allied to Cellia, but has no lateral scale tufts. Three species recorded from India. Genus. *Kertészia*, Theobald. “Ann. Mus. Nat., Hung.,” 1905, iii, p. 66. This genus has the thoracic scales hair-like, except a few narrow curved ones in front; abdominal scales long, broad and irregular. A single species, _K. boliviensis_, Theob. from Bolivia. Genus. *Manguinhosia*, Cruz. The thorax has narrow hair-like curved scales and some broad straight scales; others spatulate on the sides. Abdomen with fine hairs, except the last three segments which are scaly. Tufts of scales on the hind femora. Wing scales lanceolate. The type is _M. lutzi_, Cruz, from Brazil. Genus. *Chagasia*, Cruz. “Brazil-Medico,” 1906, xx, pp. 20, 199. This genus can at once be told by the antennal segments having many dense scaly tufts. Type, _C. fajardoi_, Lutz, from Brazil. Genus. *Calvertina*, Ludlow. _Canadian Entomologist_, 1909, xli, pp. 22, 234. The antennæ in this genus have outstanding scales on the second segment, more appressed ones on the first. At least one abdominal segment with long, flat, more or less spatulate scales. Type, _C. lineata_, Ludlow, from Philippine Islands. Genus. *Birónella*, Theobald. “Ann. Mus. Nat. Hung.,” 1905, iii, p. 69. At once told by the first submarginal cell being very small. Type, _B. gracilis_, Theob. from New Guinea. Sub-family. *Megarhininæ.* Three genera occur in this marked sub-family; they are the largest of all mosquitoes, and are very brilliantly coloured, and many have tail fans. They occur in North and South America, Asia, Africa, and Australia. The long curved proboscis is very marked. They are usually spoken of as elephant mosquitoes; some are vicious blood-suckers at times. The three genera tabulate as follows:-- α. Palpi long in both sexes. β. Last segment of ♀ palp round or blunt as if broken Genus _Megarhinus_, R. Desvoidy. ββ. Last segment of ♀ palp long and pointed Genus _Ankylorhynchus_, Lutz. αα. Palpi of female short of male long. Palpi of female not more than one-third length of proboscis Genus _Toxorhynchites_, Theobald. Genus. *Megarhinus*, Robineau Desvoidy. “Mém. Soc. d’Hist. nat. de Paris,” 1827, iii, p. 412; “Mono. Culicid.,” 1901, i, p. 215; 1903, iv, p. 163; 1907, iv, p. 128; 1910, v, p. 89. All large brilliant mosquitoes with long palpi in both sexes and, as a rule, with a caudal fan of scales; the proboscis is long and bent. They are all sylvan species, and are not so far recorded as biting man. Genus. *Toxorhynchites*, Theobald. “Mono. Culicid.,” 1901, i, p. 244; 1903, iii, p. 119; 1907, iv, p. 140; 1910, v, p. 95. Differs from the former genus in that the female palpi are short. The palpi may have one, two or three minute terminal segments. Banks’s genus Worcesteria has three. The elephant mosquito of India (_T. immisericors_), Walker, bites very severely. They are sylvan species. Sub-family. *Culicinæ*. Genus. *Mucidus*, Theobald. “Mono. Culicid.,” 1901, i, p. 268; 1910, v, p. 125. This genus is so far confined to Australia, West and Central Africa, India, East Indies and Malay Peninsula. They are all large mosquitoes, easily told by the whole body being more or less covered with long twisted scales, giving them a mouldy appearance, and the legs densely scaled with outstanding scales; the wings with large parti-coloured scales. The Australian _M. alternans_, Walker, occurs in larval form both in fresh and salt water. The adults bite man. Genus. *Psorophora*, Robineau Desvoidy. “Mém. de la Soc. d’Hist. nat. de Paris,” 1827, iii, p. 412, R. Desvoidy; “Mono. Culicid.,” 1901, i, p. 259; 1903, iii, p. 130; 1907, iv, p. 158; 1910, v, p. 123, Theobald. This genus is confined to the Americas and the West Indies. Several species exist which can easily be told from Mucidus by the absence of long twisted scales and the narrower wing scales. The legs are densely scaled and the thorax ornamented with flat spindle-shaped scales. _P. ciliata_, Robineau Desvoidy, occurs in both North and South America, and bites man. Genus. *Janthinosoma*, Arribalzaga. “Dipt. Arg.,” 1891, p. 52, Arribalzaga; “Mono. Culicid.,” 1901, i, p. 253; 1903, iii, p. 124; 1907, iv, p. 152; and 1910, v, p. 118, Theobald. Hind legs only densely scaled; some of the hind tarsi are always white. The venation is as in Culex. The abdomen is metallic and iridescent. They all bite man and occur only in the Americas and West Indies. Genus. *Stegomyia*, Theobald. “Mono. Culicid.,” 1901, i, p. 283; 1903, iii, p. 130; 1907, iv, p. 170; 1910, v, p. 151. This, the most important genus in the _Culicinæ_, can be told by the head and scutellum being clothed with flat scales and the thorax with narrow curved ones. About forty species are known in this genus, occurring in Southern Europe, Asia, Africa, Australia, the Americas, East and West Indies, and on most oceanic islands. Many of them seem to be vicious blood-suckers. They are mostly black and white mosquitoes, and several seem to go by the name of tiger mosquitoes. The genus contains the yellow fever mosquito (_S. fasciata_, Fabricius), the only one that need be dealt with in detail here. The chief known species tabulate as follows:-- A. Proboscis banded. α. Legs basally banded. Thorax brown, with scattered creamy- white scales _annulirostris_, Theobald. Thorax black, with narrow, curved golden scales _periskelta_, Giles. αα. Legs with basal and apical banding. Fore legs with no bands; mid with apical and basal bands on first and second tarsals, hind with basal bands. Thorax white in front, with a brown eye-like spot on each side _thomsoni_, Theobald. AA. Proboscis unbanded. β. Legs basally banded. γ. Abdomen basally banded. Thorax with one median silvery-white line _scutellaris_, Walker. Thorax as above, but pleuræ with white lines _pseudoscutellaris_, Theobald. Thorax similar, but two white spots near where line ends _gelebinensis_, Theobald. Thorax with two median yellow lines and lateral curved silvery lines _fasciata_, Fabr. Thorax with two short median lines and a white patch on each side _nigeria_, Theobald. Thorax with large lateral white spots in front, smaller ones by wings, two narrow median lines and two posterior sub-median white lines _lilii_, Theobald. Thorax with a white *W*-shaped area in front, a prolongation curved on each side enclosing a brown eye-like spot _W-alba_, Theobald. Thorax with white frontal median spot, two large lateral spots, a small one in front of the wings, a narrow median white line and narrow sub-median ones on posterior half. _Last two hind tarsi white_ _wellmannii_, Theobald. Thorax brown, with broad white line in front extending laterally towards wings, where they swell into a large patch, a white line on each side just past wing roots. _Last two hind tarsi white_ _albipes_, Theobald. Thorax with silvery white spot on each side in front, small one over roots of wings and white over their base. _Last two hind tarsi white_ _pseudonigeria_, Theobald. Thorax with two lateral white spots, front ones the largest, a small median one near head, two yellow median lines, a short silvery one on each side before the scutellum _simpsoni_, Theobald. Thorax with silvery-white scaled area in front and another on each side in front of wings _argenteomaculata_, Theobald. Thorax with median yellowish-white line, a silvery patch on each side in front of wings extending as a fine yellow line to the scutellum, and another silvery spot before base of each wing _poweri_, Theobald. Thorax with small grey-scaled area in front of wing roots and three short creamy lines behind _minutissima_, Theobald. Thorax (?) denuded; abdomen black; fifth segment with yellow basal band; sixth unbanded; seventh, two median lateral white spots; eighth, two basal lateral white spots; second hind tarsal nearly all white _dubia_, Theobald. γγ. Abdomen unbanded. First hind tarsal all white, second basally white, last two dark. Thorax chestnut brown, with a broad patch of white scales on each side in front and a median pale line _terreus_, Walker. ββ. Legs with white lines as well as basal bands. Thorax brown, with white lines; abdomen with basal bands _grantii_, Theobald. βββ. Fore and mid legs with apical bands, hind basal. Fourth tarsal of hind legs nearly all white _mediopunctata_, Theobald. Mid metatarsi with basal pale banding, base and apex of hind, also base of first tarsal pale _assamensis_, Theobald. ββββ. Legs unbanded. δ. Abdomen basally banded. Thorax with front half white, rest bronzy-brown _pseudonivea_, Ludlow. Thorax deep brown, with scattered golden scales, showing two dark eye- like spots; head white, dark on each side and behind _albocephala_, Theobald. Thorax brown with golden stripes; abdomen with narrow basal bands on fifth and sixth segments only _auriostriata_, Banks. δδ. Abdominal banding indistinct. Thorax with broad silvery white patch on each side in front _albolateralis_, Theobald. δδδ. Abdomen unbanded. Thorax with six silvery spots _argenteopunctata_, Theobald. δδδδ. Abdomen with apical white lateral spots. Thorax unadorned, except for pale scaled lines laterally _punctolateralis_, Theobald. δδδδδ. Abdomen with basal white lateral spots. Thorax with two pale median parallel lines and two silvery lateral spots _ininuta_, Theobald. Thorax unadorned. A white spot middle of head _tripunctata_, Theobald. No white spot _amesii_, Ludlow. AAA. Proboscis yellow basally, dark apically. Abdomen with apical pale bands _crassipes_, Van der Wulp. AAAA. Proboscis with median interrupted white line on basal half. Head black, anterior margin grey _albomarginata_, Newstead. *Stegomyia fasciata*, Fabricius (Yellow Fever Mosquito). This insect, which is the proven carrier of yellow fever, is commonly called the tiger, brindled, spotted day or striped mosquito. It is also referred to by some writers as _S. calopus_, Meigen. It is subject to considerable variation in colour, but the thoracic markings are generally very constant. The general colour is almost black to deep brown, the head with a median white area, white at the sides and in front around the eyes; the thorax has two median parallel yellow lines, a broad curved silvery one on each side and white spots at the sides; the scales on the intervening spaces of the thorax are brown. The dark abdomen has basal white bands and basal white lateral spots. The dark legs have basal white bands, the last segment of the hind legs being all white except in a variety from South America and the West Indies (_luciensis_), which has the tip of the last hind tarsal dark. The abdomen may also vary in colour, some having pale scales over most of the surface (_queenslandensis_). The food of the adult female consists mainly of man’s blood, but she will also feed on dogs and other animals. The male has been said to bite, but such is very unusual. This mosquito bites mainly in the daytime up till about 5 p.m. The adults breed the first day after emergence. They may live a considerable time, Bancroft having kept females for two months in confinement. The ova are laid separately, often in chains; they are black, oval, with a reticulated membrane outside, some of the reticulated cells containing air. They may hatch in from six to twenty hours, the larval stage nine days, the pupal stage three; thus the whole cycle may be completed in from twelve to thirteen days. The ova when dry can remain undeveloped for a considerable time. The larvæ are greyish-white, with short, thick siphon, and feed at the bottom of the water, only coming to the surface now and again to breathe. This is almost entirely a domesticated gnat, seldom being found far from man’s habitations. Its larvæ occur in such small collections of water as old sardine tins, jam-pots, calabashes, puddles, barrels, wells--in fact, wherever water is held up, even to the gutters of houses. Not only are they found breeding on land, but also on board ship, although they prefer artificial collections of water. They may also breed in larger natural collections. This insect is easily transported by steam and sailing ships and by train, and this doubtless explains its very wide distribution. The adults may live for fifty days, and it is on this account and their frequent occurrence on ships that danger lies in regard to the Panama Canal. An infected insect may leave that endemic centre of yellow fever and live until the vessel arrived at the Philippine Islands and fly ashore, and so introduce the disease for the native _fasciata_ possibly to spread. Roughly the distribution of this pest is as follows: Africa from South to North, but especially along the coast and up the Nile. In Asia, in India, Ceylon, Burma, Siam, along the ports of the Malay Peninsula, in French Cochin China, Philippine Islands, the Andaman and Nicobar Islands, Japan, Malay Archipelago, and East Indies, Turkey in Asia, Arabia and Palestine. In Australia it occurs in Queensland, New South Wales, Victoria and South Australia. In Europe in Italy, Spain, Portugal, Greece, in the Mediterranean Islands. In South America, Central America, Mexico, North America, and the West Indies it is very abundant, and it also is found in the Bahama Islands, Fiji, Sandwich Islands, Samoa, the Azores, Teneriffe and Santa Cruz, Pitcairn Islands and Bermuda. For a full account of its distribution the reader is referred to the following: “The Distribution of the Yellow Fever Mosquito (_Stegomyia fasciata_, Fabricius) and General Notes on its Bionomics;” “Mém. 1^{er} Congrès international d’Entomologie, 1911, ii, pp. 145–170, F. V. Theobald.” In addition to being the yellow fever carrier, it is supposed by Wenyon to be the intermediate host of the parasite of Bagdad sore. *Stegomyia scutellaris*, Walker. A vicious biter, found in India, China, Malay, East Indies, and Ceylon. The thorax has one median silvery stripe, and so can easily be told from _S. fasciata_. A very similar species occurs in Fiji, but can be told by the pleuræ having white lines, not spots (_S. pseudoscutellaris_, Theobald). It is the intermediate host of filaria in Fiji (Bahr). A number of nearly allied genera occur here (_vide_ synoptic table). Genus. *Theobaldia*, Neveu-Lemaire. *Theobaldinella*, Blanchard. Includes several large Culicines, of which _T. annulata_, Meigen, is the type. The wings are usually spotted (_annulata_, _incidens_, etc.), but may be nearly plain (_spathipalpis_). The males have the palpi swollen apically, and the females have long five-jointed palps. Several of these are vicious biters. *Theobaldia annulata*, Meigen. This large gnat (6 mm. long) can be told by its wings having five large spots of dark scales and by its legs having broad basal white bands to the tarsi. The larvæ occur in rain barrels and small pools. It is essentially a domestic form, occurring in houses and privies. Its distribution is Europe generally and North America. The bite is very severe, and in some districts gives rise to painful œdema.[392] [392] Theobald, “Second Report on Economic Zoology,” 1903, p. 9. _Theobaldia spathipalpis_, Rondani, occurs in Italy, Mediterranean Islands, Palestine, the Himalayas, Khartoum, and in South Africa. It is about the same size as _T. annulata_, but is yellowish-brown in colour, with striped thorax and mottled and banded legs. It occurs in privies and bites very severely. Genus. *Culex*, Linnæus. “Syst. Nat. Ed.,” 1758, x, Linnæus; “Mono. Culicid.,” 1901, i, p. 326; 1910, v, p. 322, Theobald. This large genus still contains many forms which should be excluded. The species normally have narrow curved median head-scales, and similar ones on the scutellum; the female palpi are shorter than in the former genus and the male palpi are pointed; the lateral vein-scales are narrow and linear. [Illustration: FIG. 400.--Wing of a Culex.] The type is _Culex pipiens_, Linn., the common gnat of Europe. The thorax is covered with narrow curved golden-brown scales, the abdomen has basal pale bands to the segments and the legs and proboscis are unbanded. The stem of the first submarginal cell is always less than one-fifth the length of the cell. It lays its eggs in rafts in water-butts, etc., and even in the foulest water. They are first deposited in England in June and July, and again soon after hatching in August. In some districts this gnat bites man viciously, in others not at all. The common tropical gnat (_Culex fatigans_, Wied). This resembles the European _Culex pipiens_, but can always be told by the stem of the first submarginal cell always being much longer than it is in _C. pipiens_. This is one of the species that has been proved to transmit filariæ to man, etc. Varieties of it occur in almost every country between 40° N. and S., having a very similar range to _S. fasciata_. In all countries it appears to be connected with the transmission of _Filaria bancrofti_, and it is also said to carry the micrococcus of dengue fever. Genus. *Melanoconion*, Theobald. “Mono. Culicid.,” 1903, iii, p. 238; 1907, iv, p. 507; 1910, v, p. 455. This genus is composed of eight species, most of which are small black gnats which bite viciously and which occur in swamps and jungles. They can at once be told from Culex by the veins of the wings having dense broadened scales on their apical areas and along the upper costal border. The femora and apices of the tibiæ are swollen. The black mosquito, _Melanoconion atratus_, Theob. This small gnat is a very troublesome pest in swamps in the West Indies. The female bites both by day and by night, and the bite causes severe irritation. The larvæ live in permanent ponds. It is almost black in colour, but sometimes presents a dull coppery sheen; each segment has small lateral basal white spots. Length 2·5 to 3 mm. It occurs in Para and British Guiana as well as in the West Indies. Ordinary mosquito netting is no use for keeping off this pest. Genus. *Grabhamia*, Theobald. “Mono. Culicid.,” 1903, iii, p. 243; 1907, iv, p. 284; and 1910, v, p. 277. Allied to Culex, but separated by the wings having short fork-cells, mottled scales, the median ones thick and also some of the lateral ones short and broad; the last two joints of the male palps are very slightly swollen. The eggs are laid singly, not in rafts, and the larvæ have short, thick siphons. Ten species occur and are found in Europe, North America, West Indies and Natal. _G. dorsalis_, Meigen, bites severely in Europe. _G. sollicitans_, Walker, is a great scourge along the New Jersey Coast and at Virginia summer resorts and in Florida. It breeds in brackish water and is the most common mosquito of the Atlantic seaboard. Genus. *Pseudotæniorhynchus*, Theobald; *Tæniorhynchus*, Theobald, non-Arribalzaga. Differs from the former in having the whole wing veins clothed with dense, broadish elongated scales. They occur in South America (_T. fasciolatus_, Arri.), in Africa (_T. tenax_, Theob.), in Europe (_T. richardii_, Ficalbi). The latter bites very severely. Genus. *Tæniorhynchus*, Arribalzaga; *Mansonia*, Blanchard; *Panoplites*, Theobald. _Compt. rend. heb. Soc. Biol._, 1901, iii, 37, p. 1046; “Mono. Culicid.,” 1901, ii, p. 173; and 1910, v, p. 446, Theobald. A very marked genus, easily told by the broad asymmetrical wing scales. It occurs in Africa (_T. africana_ and _T. major_, Theob.); in Asia (_T. uniformis_, Theob.; _T. annulipes_, Walker, etc.) and in Australia (_T. australiensis_); in the Americas and West Indies (_T. titillans_, Walker). The eggs (fig. 395, _d_) are peculiar in form and are laid separately; the larva has not been described; the pupa has long curved siphons. They mostly occur along rivers, in swamps and forests, and bite very severely. They also enter houses (_T. titillans_). _T. uniformis_ is most troublesome during the rains. The saliva is strongly acid. Both these species carry the larvæ of _Filaria bancrofti_. Genus. *Chrysoconops*, Goeldi. “Os Mosq. no Para,” 1905, p. 114, Goeldi; “Mono. Culicid.,” 1910, v, p. 433, Theobald. Bright yellow or yellow and purple mosquitoes, with rather dense wing scales. Numerous species occur in Africa (_aurites_, _annettii_, _fuscopennatus_, etc.), others in India, Australia and South America. Low found filariæ in the thoracic muscles of _fuscopennatus_ in Uganda. Several of the _Ædeomyina_ bite, especially the small _Uranotænias_. They are all sylvan species, seldom entering houses. They need not, therefore, be referred to here. For full details of the Culicid genera and species the reader is referred to my monograph[393] and other works mentioned below. [393] “A Monograph of the _Culicidæ_ of the World,” 5 vols. and atlas, 1901 to 1910, British Museum (Nat. Hist.); and the following: Howard, Dyar and Knab, “The Mosquitoes of North and Central America and the West Indies,” 1912; James and Liston, “The Anophelinæ of India,” Leicester, 1908; “The _Culicidæ_ of Malay,” Inst. Med. Res., Fed. Malay States, iii; _Ann.Trop. Med. and Par._, papers by Newstead and Carter; _Mem. Inst. Oswaldo Cruz_, papers by Lutz, Neva, Chagas; and the _Bulletin of Entomological Research_, etc. Other Nematocera. Other nematocerous flies are midges, daddy-long-legs and sand-flies. The ones which cause annoyance to man besides _Culicidæ_ are the following:-- Sand-flies (_Simulidæ_), certain midges (_Chironomidæ_), and a few owl midges (_Psychodidæ_). The _Nematocera_ have long thread-like jointed antennæ and their pupæ are, as a rule, naked; the larvæ have a distinct head and can thus be told from the next section (_Brachycera_). Family. *Simulidæ.* This family consists of a single genus, Simulium, Latreille, which Roubaud has recently divided into two sub-genera called Pro-Simulium and Eu-Simulium. These insects, which are frequently spoken of as sand-flies, are found in all parts of the world; they are all small insects varying from 1·5 to 3 mm. The females are very bloodthirsty, but the males appear to be incapable of sucking blood. The head sunk under the humped thorax; antennæ short, straight; palpi short and broad, of four segments, bent; wings broad and in some iridescent, legs stout. The male has holoptic eyes, whilst in the female they are small and widely separate. The sucking proboscis is short. The thorax and abdomen are clothed with short hairs which may form spots and markings; these are golden, silvery, grey, or brownish. In the sub-genus Pro-Simulium the second segment of the hind tarsi in both sexes is elongate, linear, and without a basal notch; in Eu-Simulium it is short, curved, and dorsally notched at the base. _Simulidæ_ often occur in swarms, and attack not only man but cattle, horses, and poultry. In some districts they are more annoying than mosquitoes. Their life-cycle has been most completely worked out by King, in Africa. The larvæ and pupæ occur in swiftly flowing water, by waterfalls, in rapids, etc. The ova are laid in gelatinous masses on plants or rocks close to or overhanging the water. The larva is cylindrical, enlarged posteriorly, where it is provided with a sucker, by means of which it attaches itself to a rock, water weeds, debris, etc.; anteriorly it has a proleg close behind the head on the lower surface. The head is dark and chitinous. The respiration takes place by means of branched tracheal gills which protrude from the dorsal surface of the last body segment; they are retractile. The colour varies from deep green to yellow or almost black. Their food consists of algæ and other organisms in the water brought to their mouth by two fan-like organs placed on the head. The larvæ can crawl from place to place by means of the thoracic proleg; they occur in masses, usually in a more or less erect attitude. A network of threads is spun on their support, by means of which King tells us “they are enabled to maintain their position against the strongest current; frequently they will leave their support and let themselves out into the stream anchored by threads of silk and enabled by them to return.” When full fed the larva spins a pocket-shaped cocoon on the support, within which it pupates. The pupa is motionless and has a pair of branched spiracles projecting from behind the head. When the adult emerges, a bubble of air collects around it, and in this it floats to the surface and at once takes wing. The European species take a month to complete larval life, a week being spent in the pupal stage. The flies are most restless, and even when stationary continually move their legs about like feelers. Sometimes the swarms consist entirely of females, sometimes early in the season mostly of males. The females pierce the skin of humans on tender spots, such as ears, the forehead, around the eyes and nose, and crawl into the cavities. They are quite harmless at night, mainly attacking about sunrise and sunset. Some crawl up the arms and legs and down the neck, and leave behind little red weals which itch intensely (_S. damnosum_, Theob.), and blood may flow freely from the wounds. The following are some of the worst species:-- _Simulium columbaschensis_, the “Kolumbatz fly,” which abounds in the damp marshy lands along the Danube, and is a great plague to man and beasts in Hungary, and is also abundant in Austria and Moravia, and is most numerous after inundations from the Danube. They sometimes appear in such swarms that it is impossible to breathe without getting them into one’s mouth. There are instances of children being killed by these flies when left on the ground by their mothers when working in the fields. _S. damnosum_, Theob. This occurs throughout Equatorial Africa and is known as the “jinja fly” in Uganda, the “fouron” in the French Congo, the “kilteb” in the Sudan. It is a most vicious biter, and in some parts occurs in “belts”; Dr. Christy found one such extending from the shores of the Victoria Nyanza northwards along the right bank of the Nile for twelve or fifteen miles or more, and perhaps three or four miles wide. In this area the flies swarm in millions at certain seasons, so much so that the natives have to leave their plantations. The bite causes a weal, marked by a drop of blood. _S. griseicollis_, Becker. The so-called “nimitti” occurs in Upper Egypt and the Anglo-Egyptian Sudan. It lives near the river and is not found more than half a mile from it. Human beings are bitten on the face and hands, animals in the region of the pudenda. _S. latipes_, Meigen. This is a European species, also found in Natal. _S. wellmanni_, Roubaud. The “ohomono” of Angola, where it bites viciously and is dreaded by the naked porters. _S. buissoni_, Roubaud. Occurs in abundance in the Marquesas Islands. It has been _suggested_ that this species may help to propagate leprosy.[394] [394] _Bull. du Mus. d’Hist. nat._, 1906, xii, p. 522. A large number of these insects have been described by Lutz in Brazil.[395] [395] _Mem. Inst. Oswaldo Cruz_, 1910, ii, fasc. 2, pp. 211–267. A _Simulium_ sp. (?) is very harmful to poultry in Cape Colony.[396] [396] C. Fuller, “A New Poultry Pest,” 1899, Leaflet No. 1, Dept. Agric. In America, _Simulidæ_ are most annoying. One, _S. meridionale_, Riley, also known as the turkey gnat in the Mississippi Valley, has been supposed to be the carrier of chicken cholera; anyhow, it has caused the death of thousands of chickens and turkeys in Virginia annually.[397] [397] _Insect Life_, 1888, i, p. 14. In Mexico Townsend found a Simulium which was named _S. occidentalis_, which caused great annoyance to man, many people being so susceptible to them as to preserve through the gnat season a chronic inflammation of the exposed parts of face and neck, resulting from the repeated bites giving rise to sores.[398] [398] _Ibid._, 1893, v, p. 61. Men and horses have been partially incapacitated by the bites of sand-flies or Simulium in a Hampshire wood (Cantlie, _Brit. Med. Journ._, April 28, 1900, v, No. 2,052, p. 1023). [Illustration: FIG. 401.--Wing of Simulium.] [Illustration: FIG. 402.--Wing of Chironomus.] Family. *Chironomidæ* (Midges). The _Chironomidæ_ or midges are not only frequently mistaken for mosquitoes, but some are very annoying to man by biting him as mosquitoes do. They are easily distinguished from true mosquitoes (_Culicidæ_) by the following characters: (1) head small, often retracted under the cowl-like thorax; (2) no scales to the wings or body; and (3) the different arrangement of veins on the wings (fig. 402). Two genera are important as annoying man, namely, Culicoides, Latreille, and Johannseniella, Williston. The larvæ of _Chironomidæ_ are either aquatic, both fresh water and marine, and help to make the former foul,[399] according to Slater, or may, as in _Ceratopogoninæ_, live beneath the bark of trees, etc. The pupæ are very varied and also the life-histories of the different genera.[400] The blood-sucking habit is confined to the sub-family _Ceratopogoninæ_. [399] _Entomologist_, 1879, p. 89. [400] Theobald, “An Account of British Flies,” i, p. 172. Sub-family. *Ceratopogoninæ.* This sub-family of midges consists of very small species varying from 1 to 2 mm. in length; the wings have darkened areas, and the second longitudinal vein is wanting, and the first and third veins are stouter than the others and placed close to the anterior margin, the fourth and fifth are forked; the antennæ in both male and female are composed of fourteen segments, six or eight in the males bearing long hairs. The chief blood-sucking species belong to the genera Culicoides, Latreille, and Johannseniella, Williston. The latter genus differs from the former in the absence of an empodium or median appendage on the last segment of the tarsi. The genus Ceratopogon, as restricted by Kieffer, is not supposed to take vertebrate blood, but Austen has recently noticed that the type specimen of _C. castaneus_, Walker, and a new species described by him, apparently have their bodies distended with blood. The wings in the _Ceratopogoninæ_ are carried flat when at rest. [Illustration: FIG. 403.--A Ceratopogon, or midge. Greatly enlarged.] In spite of their small size the females are the most bloodthirsty and annoying of all insects. The Culicoides, which are often called “sand-flies,” bite during the day and rarely at night. Usually they are most troublesome between 3 and 6 p.m. They frequently attack in swarms, especially in the open, and owing to their minute size can get through fine mosquito netting. Some of them produce a distinct “buzz” when on the wing. These insects are found in all parts of the world. No species has been definitely connected with any disease, but Culicoides has been suspected of carrying the germs of Delhi boil. The larvæ of Culicoides are elongate in form and have smooth bodies composed of thirteen segments including the head, which is horny; there is no proleg on the first segment as seen in Chironomus, and on the anal segment are retractile gills. They are very active and live in the sap of various trees which saturates diseased bark. The pupæ are smooth, but the abdominal segments bear a transverse row of small spines. Austen describes a number of Culicoides and one Johannseniella and three Ceratopogons from Africa,[401] and Lutz[402] a number of this sub-family from Brazil, including a new genus, Centrorhyncus. Another genus, Tersesthes, Townsend (Centrotypus, Grassi; Mycterotypus, Noe), also occurs in Brazil. [401] _Bull. Ent. Res._, 1912, iii, pp. 99–108. [402] _Mem. Inst. Oswaldo Cruz_, 1913, v, fasc. 1, pp. 45–72, pls. 6–8; and 1914, vi, fasc. 2, pp. 81–99. _Culicoides ornatus_, Taylor, is described from Townsville, Australia, found in mangrove swamps. It is a very vicious biter and causes considerable irritation, settling on hands and wrists (Taylor, _Rep. Ent. Aust. Inst. Trop. Med._ (1912), 1913, p. 24). Family. *Psychodidæ* (Owl Midges). This family of diptera is of considerable importance, not only on account of the blood-sucking habits of some species, but especially on account of one at least having been proved to be the carrying agent of “papataci” fever, a three-day fever very prevalent in Malta and several parts of Southern Europe in the autumn. It is also possible that these small flies are connected with the formation of “Delhi boil,” caused by a protozoan parasite. [Illustration: FIG. 404.--An owl midge, _Phlebotomus_ sp. Greatly enlarged. (From Giles’s “Gnats or Mosquitoes.”)] _Psychodidæ_ are all very small flies, many of which have a moth-like appearance, and owing to their fluffy nature are spoken of in Britain as “owl flies,” sometimes also as “window flies.” Their bodies and wings are covered with hairs, densely in some (sub-family _Psychodinæ_), and in a few with patches of flat squamæ. In the non-blood-sucking _Psychodinæ_ the wings are carried in a peculiar manner downwards over the body, to a _slight extent_ resembling the _Hepialidæ_, or swift moths. The wings may be ovoid or lanceolate, and have a marked venation as seen in the figure. The proboscis is short and non-suctorial in the majority of genera, but in the sub-family _Phlebotominæ_ it is elongated and hard. The antennæ are long and of sixteen segments, and bear whorls of fine hair. There are two sub-families, _Psychodinæ_ and _Phlebotominæ_; in the former the mouth is not suctorial; the female has a horny ovipositor and the second longitudinal vein is branched at the root of the wing; in the second sub-family the proboscis may be formed for sucking, the female has no horny ovipositor, and the second long vein has its first fork near the middle of the wing. The sub-family _Phlebotominæ_ contains the genus Phlebotomus, which occurs in South Europe, South Asia, Africa, North and South tropical America. They are all small grey, brown, or dull yellow-coloured flies, and carry their wings when at rest upwards like a butterfly. The proboscis is moderately long and the legs long and thin. The females are most vicious blood-suckers, but in some species anyhow the males also bite (_P. duboscii_). They are mainly nocturnal feeders and hide away during the day in any dark corners or crevices. The life-cycle has been worked out by Newstead[403] and Grassi[404] in Europe, and by Howlett[405] in India. [403] _Bull. Ent. Res._, 1911, ii, pt. 2, pp. 47–78. [404] “Ricerche sui Flebotomi,” _Mem. della Soc. ital. della Scienze_, 1907, ser. 3, xiv, pp. 353–394. [405] “Indian Sand-flies,” _Ind. Med. Cong._, 1909, sec. III, pp. 239–242. The larvæ have been found in crevices in rocks and caves, in dirty cellars, and dark damp places containing rubbish, and are also said to live in crevices in the walls of privies and cesspits. The minute larva is very marked; as figured by Newstead it has two long chætæ projecting upwards, in some stages branched, in others simple, and on the segments a few blunt spine-like processes. The pupæ are found in similar situations. The ova are very minute, elongate, translucent white, and covered with a thin coating of viscous matter when first laid; soon after they become dark brown, shiny, with long black wavy lines. Newstead found the incubation period in Malta to last for about nine days in _P. papatacii_. Five species are known in Europe, five in Africa,[406] two in North America, and eight are described by Annandale[407] in the Oriental region. Lutz and Neiva have described three species from Brazil[408] (_P. longipalpis_, _intermedius_ and _squamiventris_). [406] Newstead: _Bull. Ent. Res._, 1912, iii, pp. 361–367. [407] _Rec. Ind. Mus._, v, pt. 3, Nos. 13 and 14. [408] _Mem. Inst. Oswaldo Cruz_, 1912, iv, fasc. I, pp. 84–95. *Brachycera* (Flies). The antennæ as a rule have three segments, and are usually shorter than the head. The first segment of the antennæ is frequently very small, and the third one is generally the largest, and sometimes possesses a terminal annulated bristle. The palpi have from one to three segments; the mandibles are covered by the labium. The three thoracic rings are coalesced; wings are almost always present, the posterior ones being rudimentary and covered with a little scale. From the ova legless maggots are hatched, which as a rule have not a distinct head, but occasionally possess two claw-like hooklets. These maggots live in decomposing organic matter; they rarely live in water and some of them are parasitic. They either become barrel-shaped pupæ within the last larval integument or, after casting it, are transformed into naked pupæ. The larvæ of numerous _Brachycera_ have been observed in man, some in ulcers or on mucous membranes, others in the skin or in the intestine, etc. In many cases the report only mentions the presence of the larvæ of flies; in other cases the species has been determined; whilst in still other cases the corresponding adult creature is unknown. We must therefore confine ourselves to describing the most common varieties. Family. *Phoridæ.* These flies belong to the same division of _Diptera_, the Aschiza, as the family _Syrphidæ_ or “hover flies.” They are all small insects with marked antennæ and wings; the former have the third segment globular and enlarged, and thus hiding the first two; the wings are short and broad, the venation shows two short, thick, long veins with four thin ones running out from them. The larvæ normally live in decaying animal and vegetable matter, but one species, _Aphiochæta ferruginea_, Brun., has been found as an intestinal parasite of man. *Aphiochæta ferruginea*, Brun. This small fly belonging to this family is of an orange-ochreous colour, the upper part of the thorax tawny, and with dark bands on the abdomen, legs pale yellow, the hind femora tipped with dark brown. It measures only 2 to 3 mm. in length. This insect is shown by Austen to be widely distributed in the tropics, being found in India, Burma, West Africa, and Central America. The larvæ breed in decaying animal matter, such as putrid meat, decomposing shell-fish, etc. Heusner bred out sixty-three flies from larvæ taken from an Indian’s foot. Baker (_Proc. Burma Branch Brit. Med. Assoc._, 1891, p. 11–16) found that the maggots of this fly were passed _per anum_ by a European at intervals during a period of ten months. Baker found that the larvæ fed on human fæces; from the egg stage to the deposition of eggs from the resultant brood of flies occupied twenty-two days. He concludes that they are capable of propagating, and do so while living within the human intestines. He also records the larvæ in two girls. The larva does not seem to have been described, but Austen describes the pupa (_Trans. Soc. Trop. Med. and Hyg._, iii, No. 5, p. 229). *Phora rufipes*, Meig. The larvæ of the “hump-backed fly” live in rotting potatoes, mushrooms, radishes, etc., and when accidentally introduced into the intestine of man can, like other larvæ, live there twenty-four hours and even more, and may set up serious gastric disturbances. _P. rufipes_ is the same as _P. pallipes_, Latr. Family. *Sepsidæ.* Small blackish flies, elongate, with abdomen narrowed at the base, thickened and curved downwards towards the extremity. Larvæ often found in decaying vegetables, ham, cheese, etc. The larvae have the power of skipping; conical in form, pointed in front, truncated behind, about 5 mm. long, shiny and smooth, the anal segment with fleshy protuberances. The genus Piophila has a short proboscis and the cross-veins of the wings approximate. *Piophila casei*, L. Cheese flies. The larvæ live in ripe cheese, with which they are sometimes introduced into human beings (Meschede). The larvæ of the cheese flies (_Piophila casei_) may pass through the alimentary canal of human beings alive, and have been occasionally referred to in cases of internal myiasis. It also breeds in dead bodies in adipose tissue. Howard records it on human excrement. It is thus possible that some of the recorded cases of this pest being passed alive may be due to eggs deposited on human fæces. Family. *Syrphidæ* (Hover and Drone Flies). Amongst the large family of _Syrphidæ_ is found a section known as the _Eristalinæ_ or drone flies, whose curious long-tailed larvæ are popularly called “rat-tail larvæ,” on account of the end of the body being drawn out into a long telescopic tail of two segments, at the end of which are placed the breathing pores. These larvæ live in water, no matter how foul, and in liquid manure. They have occasionally been obtained in foul drinking water by human beings and from eating watercress improperly washed or from badly kept beds. Austen (_Trans. Soc. Trop. Med. and Hyg._, iii, No. 6, p. 221) records that in the autumn of 1907 a number of the larvæ of the common drone fly (_Eristalis tenax_) were passed _per rectum_ by a woman in Hampshire who had recently arrived from France. The patient had eaten a considerable quantity of watercress before leaving France. I have twice found small Eristalis larvæ clinging by their long tails on watercress served at table. Family. *Drosophilidæ.* Small, rather plump flies, with short, broad abdomen, with bristles on the head and legs. Often abundant in decomposing fruit, and may occur in dense masses. *Drosophila melanogaster*, Br. The larvæ of this fly occur in over-ripe fruit and in fungi, often also in human habitations, and live in substances undergoing acid fermentation (vinegar, decaying fungi, rotting fruit, in damaged spots in diseased trees), much more rarely in animal substances, and they occasionally gain access to the human intestine (for example, by the medium of sour milk). When introduced in any quantity, they cause vomiting or attacks resembling colic; when taken in the pupal stage no unpleasant results are produced. Family. *Muscidæ.* *Teichomyza fusca*, Macq. Syn.: _Scatella urinaria_, Rob. Desv.; _Ephydra longipennis_, Meigen. The larvæ live in the urine in privies. Several authors state they have found them in fresh fæces or in vomited matter. Pruvot states that they continue for three days in the stomach of rats into which they have been intentionally introduced. (Pruvot, G., “Contrib. à l’étude des larves de dipt, trouv. dans le corps humain,” _Thèse de Par._, 1882; Chatin, J., in _Comp. rend. Soc. de Biol._, Paris, 1888 (8), v, p. 396; Roger, H., _ibid._, 1851 (1), iii, pp. 88, etc.) *Homalomyia canicularis*, L., etc. _Homalomyia manicata_, Meig., live as larvæ in decomposing vegetable matter or in cultivated vegetables (cabbage); they are easily recognizable by their plumed bristles, which are situated laterally on the body segments. They obtain access fairly often to the human intestine and give rise to very uncomfortable symptoms. Cases have been recorded from Germany, Austria, France, England, North America (Wacker, in _Artzl. Intelligenzbl._, 1883, xxx, p. 109; Florentin, in _Compt. rend. Soc. de Biol._, Paris, 1904, lvi, p. 525; and other authors). The larvæ of an allied genus (Anthomyia), which, however, does not possess plumed bristles, has been found in the external auditory meatus of a man (_A. pluvialis_, according to Danthon). [_H. canicularis_ is common to Europe and North America, and is an abundant house-fly. It is the small house-fly so often seen on windows. Besides living on vegetable matter, they have also been found in the nests of the humble bee. Larvæ of this species (fig. 405) were sent to the British Museum, taken from the fæces of a woman suffering from cancer.[409] They were found at Shrewsbury. Hagen[410] reports the larvæ of this fly as occurring alive in the urethra of a patient.--F. V. T.] [409] Theobald, “First Report Economic Zoology,” _Brit. Mus. (Nat. Hist.)_, p. 55. [410] Hagen, _Proc. Bost. Soc., N.H._, xx, p. 107. *Homalomyia scalaris*, Fabr. [This is not a synonym of the above, but a distinct species. [_H. manicata_, Meigen, is also distinct.--F. V. T.] *Anthomyia desjardensii*, Macq. This fly, allied to Homalomyia, is the cause of both intestinal and cutaneous myiasis at Bihé, Angola (Wellman, _Journ. Trop. Med. and Hyg._, June, 1907, x, p. 186). *Hydrotæa meteorica*, L. The larvæ live in decaying vegetable substances, also in dung, and have been evacuated in some cases by man (Zetterstedt, Joseph). [Illustration: FIG. 405.--Larva of _Homalomyia canicularis_. Enlarged.] [Illustration: FIG. 406.--Larvæ of _Calliphora vomitoria_. Enlarged.] [Illustration: FIG. 407.--Larva of _Chrysomyia macellaria_. 4/1. (After Conil.)] *Cyrtoneura stabulans.* Larvæ in fungi, but occasionally also on larvæ of butterflies and _Hymenoptera_; occasionally introduced into the human intestine (Joseph). *Musca domestica*, L., and _M._ (_Calliphora_) _vomitoria_, L., and allied species; larvæ of these have been repeatedly found in the intestine and nose of man (Mankiewicz, etc.).[411] [411] “Larvæ of a Musca, probably _M. corvina_, were passed in numbers _per rectum_ by a child in Liverpool with Homalomyia larvæ,”--“Second Report Economic Zoology,” Theobald, 1903, p. 16. *Musca domestica*, Linn. (Common House-fly). It is not only on account of a few larvæ of the common house-fly (_Musca domestica_) being found in the intestines of man that it is of importance medically. It is far more important on account of the part it plays in the spread of diseases of the intestines, such as typhoid fever and cholera, infantile diarrhœa and dysentery. Howard and Clark (_Journ. Exp. Med._, 1912, xvi, No. 6, pp. 850–859) have shown that the house-fly is capable of carrying the virus of poliomyelitis for several days on the surface of the body and for several hours in the gastro-intestinal tract. The house-fly may also distribute the ova of _Tænia solium_ and the white worms (Oxyuris and Ascaris). It has also been proved that they may carry the germs of tuberculosis, and it is said that they play an important part in the spread of infectious ophthalmia in Egypt. This insect is found in all parts of the world. In warm countries it breeds all the year round, and it may do so even in temperate climates in warm places, such as stove houses. Most, however, die off in the autumn; but some survive the winter as adults, in such places as kitchens, restaurants, and warm houses. I have never failed to find a few _Musca domestica_ in houses during the winter. The majority, however, hibernate as puparia. The females deposit from 120 to 150 eggs in a batch in stable manure, rotting vegetation, house refuse, spent hops, old soiled bedding, etc. A single female may lay as many as six batches of ova during her life. The eggs are shiny white, and hatch in from eight to twenty-four hours in warm weather to three or four days in cool weather. The white footless maggots are cylindrical, tapering to a point at the head end, truncated posteriorly. The head consists of two dark mandibular hooks and two short antennæ. On the tail end are two plates, the stigmata, in which the main tracheal trunks open; in the second segment are a small pair of projecting stigmata. The larval stage lasts from seven to five days in hot weather; but in cold weather in temperate climes it may last six or eight weeks. The larva on reaching maturity becomes a barrel-shaped puparium of a dark brown to black colour, and in this case changes to the pupa. This stage lasts from three days in the tropics to four or five weeks in cold weather, the life cycle thus varying from ten days in the tropics to fourteen in warm weather in Europe up to three or four months under unfavourable conditions. All breeding grounds should be burnt or otherwise done away with, such as stable manure, house and kitchen refuse, human excrement and soiled substances, also decaying vegetation as soon as possible, certainly by every sixth day. Stable manure should be kept in closed receptacles and should be removed by every sixth day to at least one mile from habitations and sprinkled with chloride of lime. All kitchen and household refuse should be burnt at once or buried in pits and covered with soil. Latrines should be as far as possible from hospitals, mess rooms and tents. Food--especially milk, sugar and fruit--should be kept screened with muslin when house-flies are about. Mess rooms and tents and hospitals should have doors and windows screened with fine wire gauze during the fly season. All possible steps should be taken to prevent them contaminating man’s food and from breeding in human excrement and from entering hospitals. When present in dwelling-houses in numbers they may be killed by fumigation with pyrethrum or sulphur. Genus. *Chrysomyia*, Rob. Desv. *Chrysomyia* (*Compsomyia*) *macellaria*, Fabr.; *Lucilia macellaria*, Fabr. Syn.: _Lucilia hominivorax_, Coq.; _Calliphora infesta_, Phil.; _Calliphora anthropophaga_, Conil. A species distributed from the Argentine to the south of the United States which deposits its ova on ulcers, in the aural meatus or in the nasal cavities of persons who sleep in the open air. The larvæ are yellowish white, 16 mm. long, are armed with two strong mouth hooks, and provided with spinous rings (screw-worm); they lie hid in the nasal and frontal sinuses, in the pharynx, larynx, etc.; they perforate the mucous membranes, even cartilage, migrate into the eyes, the cranial cavity, middle ear, and cause severe disturbances; after the mature stage, in which the larvæ leave the host to enter the pupal state, these symptoms often spontaneously abate after a lapse of eight days, leaving behind greater or less cicatrices, and consequently also defects in function of the organs attacked. Very often, however, sepsis sets in, usually with a fatal termination. (Coquerel in: _Arch. gén. de méd._, 1858 (5), p. 513; 1859, xiii, p. 685; _Ann. Soc. ent. France_, 1858 (3), vi, p. 171; 1859, vii, p. 234. Weber in: _Rec. de mém. de méd. milit._, 1867 (3), xviii, p. 159. Francius, A., in: _Arch. f. path. Anat._, 1868, xliii, p. 98. Conil in: _Bol. Acad. nac. cienc. Cordoba_, 1881, iii, p. 296. Humbert, Fr., in: _Proc. U.S. Nat. Mus._, 1883, vi, p. 103; _Amer. Nat._, 1884, xviii, p. 540. Lindsay in: _Journ. Trop. Med._, 1902; v, p. 220, and other authors.) [Illustration: FIG. 408.--The screw-worm fly (_Chrysomyia macellaria_).] [This species is known as the screw-worm fly. It attacks animals as well as man, especially laying its eggs on wounds formed by barbed wire. It may also be found on dead flesh. Dr. St. George Gray sent me specimens from St. Lucia, from the nose and mouth of a patient in Victoria Hospital. Others were found in the vagina of another patient. Out of the four patients attacked, two occupied the same bed, one after the other, and a third the next bed to it. The other case was in a more remote part of the hospital. There are numerous records of this fly attacking man. It occurs from the Argentine to Texas.--F. V. T.] *Chrysomyia viridula*, Rob. Desv. [This species is somewhat larger than the former; the body is metallic bluish-green, the dorsum of the thorax with three blackish, longitudinal stripes, and the face ochraceous; about 10 mm. long. Austen records this species from man, Dr. Daniels having bred it from larvæ from a sore on a human being in New Amsterdam, British Guiana. Dr. Laurence also bred it in Trinidad. In the latter case between 100 and 150 maggots were discharged from the nose of a woman suffering from facial myiasis (_Brit. Med. Journ._, January 9, 1909, p. 88 + fig.).--F. V. T.] Genus. *Lucilia*, Rob. Desv. *Lucilia nobilis*, Meig. The larvæ were observed by Meinert in Copenhagen in the auditory meatus of a person who, after taking a bath, fell asleep in the open air, and on waking felt singing in the ears, and had a sensation as if there were water in the auditory canal. During the next days severe pains set in, and there was a discharge of blood and pus from both ears, as well as from the nose. On washing out the meatus the maggots made their appearance. _Lucilia cæsar_ and _L. sericata_ have also been observed in the larval state in man (Thompson, Hope, Henneberg and Calendoli, Napoli, 1907). [This golden-green fly usually lays its eggs on decomposing organic matter; now and again it lays its eggs in wounds on man.--F. V. T.] Genus. *Pycnosoma*, Brauer and v. Bergenstamm. The species of this genus have a general resemblance to the Lucilias and Chrysomyias, but the body is stouter and the abdomen banded. The genus can be distinguished from Chrysomyia by the absence of the three thoracic stripes and by the eyes of the male, in which the facets forming the upper portion are much enlarged, whereas in Chrysomyia they are not noticeably larger. Austen also points out that the sterno-pleural bristles in Pycnosoma are 1 : 1, in Chrysomyia 2 : 1. The genus is found in tropical Asia and Africa only. All records of Chrysomyia (Compsomyia) in India must be referred to this genus. Bezzi and Stein (“Katalog der Palăarktischen Dipteren,” 1907, iii, p. 543), however, regard the two as synonymous. The larvæ are frequently found in the nostrils of man and burrow into the sinus, but normally they live on decaying animal matter. Pycnosoma forms the so-called Indian screw-worm. Patterson (_Ind. Med. Gaz._, October, 1909, xliv, No. 10) records the case of a woman at Tezpin, Assam, from whom as many as 100 larvæ were removed at one time, and later the left orbital cavity was found packed with hundreds of maggots; eventually the patient died. It is possible that this, however, was due to a species of Sarcophaga. Austen undoubtedly records this genus causing nasal myiasis in India (_Trans. Soc. Trop. Med. and Hyg._, iii, p. 235). At Dehra Doon, U.P., a woman discharged 100 larvæ from her nose, with great pain in the nasal region and frontal sinuses. The so-called “peenash,” a common malady in Rajputana, is a true nasal myiasis. Genus. *Sarcophaga*, Mg. *Sarcophaga carnosa*, L., 1758. Larvæ of flesh-flies provided with two claws at the anterior end, which settle on raw or cooked meat, and in the open on carcases of animals; they are often observed in man, both in the intestine (introduced with food) and in the nasal cavities, frontal sinus, conjunctiva, aural meatus, anus, vulva, vagina, prepuce, and open ulcers, often migrating further from the regions first attacked. (Gayot in _Compt. rend. Acad. Sci._, Paris, 1838, vii, p. 125. Grube in _Arch. f. Naturg._, 1853, xix, 1, p. 282. Legrand du Saulle in _Compt. rend. Acad. Sci._, Paris, 1857, xlv, p. 600, and other authors.) [This fly is viviparous. The fly varies from 10 to 30 mm. in length, and is of a general ash-grey colour; the thorax with three dark stripes, the abdomen light grey with three black spots on each segment; legs black; base of wings yellow. It also attacks animals and birds, especially geese. The genus Sarcophaga is universally distributed. The maggots are whitish or yellowish footless larvæ of twelve segments, tapering to a point in front, broadened posteriorly. There are two mouth hooks, by means of which they rasp their food. The breathing pores are at the end and consist of two groups of three slits, each surrounded by a hardened area. They pupate in their old skin, which turns brown.--F. V. T.] *Sarcophaga magnifica*, Schiner, 1862.[412] Syn.: _Sarcophaga wohlfahrti_, Portschinsky, 1875. [412] [The correct name for this fly is _Wohlfahrtia magnifica_, Schiner.--F. V. T.] A species widely distributed over the whole of Europe, occurring especially in Russia (Mohilew); the presence of the larvæ in man was first observed by Wohlfahrt (1768). The larvæ settle in the pharynx, in the nose, the aural meatus, the conjunctiva, and in other regions of the human body; they also attack domestic animals and birds. As Portschinsky has shown, they cause severe inflammations, hæmorrhages and suppurations in the organs in which they occur; children are especially attacked. A number of cases have been observed also in Central and Western Europe. [The fly has a light grey abdomen with shiny black spots which do not change their shape and appearance according to the angle in which the fly is viewed.--F. V. T.] (Wohlfahrt: “Observ. de vermibus per nares excretis,” Halæ, 1768; _Nov. Act. Acad. Caes. Nat. curios._, 1770, iv, p. 277. Gerstäcker in: _Sitzungsb. Ges. nat. Frde. Berl._, 1875, p. 108. Portschinsky in: _Horæ soc. entom. ross._, 1875, 1884, p. 123. Laboulbène in: _Ann. Soc. ent. France_, 1883 (6), iii; _Bull._, p. xcii. Leon in: _Bull. Soc. des Méd. et Nat. de Jassy_, 1905, xix, p. i. Freund, L., in: _Verh. Ges. deutsch. Naturf. u. Ärzte_, Homburg (1902), 1902, ii, 2, p. 450, and other authors.) [Probably most cases of attack in Europe are due to this species.--F. V. T.] The above cited do not exhaust the number of observations of diptera larvæ parasitic in man; there are yet to be mentioned the larvæ of _S. hæmorrhoidalis_, _S. hæmatodes_ (of G. Joseph), those of _S. ruficornis_ (excitants of a cutaneous myiasis in the East Indies), those of species of Eristalis (of Hanby and others), and those of _Phora rufipes_ (of Kahl, of Warsaw, and others). In many cases the determination of the diptera larvæ has been omitted (or must be omitted); such is the case with diptera larvæ in the eye (Schultz-Zehden in: _Berl. klin. Wochenschr._, 1906, p. 286. Ollendorf in: _Med. Korrespondenzbl. d. würt. ärtzl. Landesver._, 1904, p. 1017. Kayser in: _Klin. Monatsbl. f. Augenheilkunde_, 1905, xliii, i, p. 205. Ewetzky and v. Kennel in: _Zeitschr. f. Augenheilkunde_, 1904, xii, p. 337, and other cases). Austen records several cases of myiasis due to Sarcophaga (_vide Trans. Soc. Trop. Med. and Hyg._, 1910, iii, No. 6). The larvæ of African _Muscidæ_ have now become of greater interest; like several Oestrid larvæ they live normally in the skin of mammals, but also attack man. The knowledge of these species is certainly very insufficient, but this is not likely to be the case much longer, as medical men practising in the Colonies are giving their attention to these parasites. At the present time four distinct forms are recognized according to Gedoelst.[413] [413] [The following are known to cause myiasis in man in Africa: _Cordylobia anthropophaga_, Grünb.; _Auchmeromyia luteola_, Fabr.; _A. rodhani_, Gedoelst; _Oestrus ovis_, Linn.; and _Anthomyia desjardensii_, Macq. The _anthropophaga_, Blanchard, and the _depressa_, Walker, referred to here are Grünberg’s _anthropophaga_.--F. V. T.] *Sarcophaga chrysotoma*, Wied. [This species is recorded as attacking human beings at New Amsterdam, British Guiana. The fly is 15 mm. long, has a golden-coloured face, three broad black thoracic stripes and ochraceous buff anal segments. It was bred from larvæ obtained by Dr. Roland from a sore on a girl’s foot. It is known to occur in the Brazils and the West Indies. Another species was also bred which Austen was unable to identify.--F. V. T.] *Sarcophaga plinthopyga*, Wied. [This and other species of Sarcophaga are called “yaw flies” in Dominica, as they are believed to be concerned in the dissemination of frambœsia or yaws (Nicholls) (_vide_ Austen, _Trans. Soc. Trop. Med. and Hyg._, 1910, iii, p. 239).--F. V. T.] *Ochromyia anthropophaga*, E. Blanch.; *Cordylobia arthrophaga*, Grünberg. [Illustration: FIG. 409.--Ochromyia larva on the skin of man, South Africa. 3/1. (After Blanchard.)] Indigenous to the Senegal and neighbouring districts; in the district of Cayor (between the mouth of the Senegal and Cape Verde) the larva is known as the “ver de Cayor.” It lives under the skin, especially at the lower extremities and the lower region of the trunk, producing small boils, which cause pain, but after about eight days, when the larva leaves the body to enter the pupal stage, the pain discontinues. Besides man the larva occurs in dogs, goats, cats, and in the jackal. It is still questionable whether the fly deposits its eggs direct or on the ground, from whence the larvæ as they emerge gain access to animals and man. Larvæ yellowish-white, 14 mm. long, 4 mm. wide, eleven segments[414]; head with two globular antennæ-like appendages, two black curved mouth hooks, and two wart-shaped, finely spinous structures at their base. Body evenly covered to the seventh segment with small black prickles, which are stronger at the sides and the anterior borders of the segments; from the seventh they increase in size, on the two hindermost they are wanting; on the last segment two deep yellow spiracles, each with three markedly curved fissures; in addition two stigmata on the posterior border of the first segment. Duration of the larval stage about eight days. Upon the construction of roads in Guinea the larva is spread by dogs far into the interior. [414] [Austen gives the length as 12 to 12·5 mm. and the breadth as 5 mm.; he describes the larva as follows: Bluntly pointed at the anterior extremity, and truncate behind; from third to eleventh segments thickly covered with minute recurved spines of brownish chitin, usually arranged in transverse series of groups of two or more, which can be seen to form more or less distinct undulating and irregular transverse rows. In each of the two posterior stigmatic plates, the respiratory slit on either side of the median one is characteristically curved, resembling an inverted note of interrogation. The barrel-shaped puparium is on an average 10·3 by 4·6 mm.; its colour varies from ferruginous to nearly black.--F. V. T.] *Auchmeromyia* (*Bengalia*) *depressa* (Walker).[415] [415] [According to Austen this is _Cordylobia anthropophaga_, Grünb. _Bengalia depressa_, Walker, is a very different insect, whose life-history is unknown.--F. V. T.] [Illustration: FIG. 410.--Head end of “larva of Natal.” Magnified. (After Gedoelst.)] Distributed in the region of Natal and apparently over the whole of South Africa. The “larva of Natal,” as one may still term the species provisionally, as its identity is not certain, possesses on its head (besides the mouth hooks) lateral protuberances beset with a row of chitinous spines. The cuticle of the body is spinose. The spines are difficult to recognize on account of their transparency and want of colour; they are longest over the anterior segments, from the fifth they become smaller, and over the hindermost they are very small. Apart from the foremost segment, the position they take is that of rows running transversely or obliquely, two to four generally in juxtaposition; the number of spines in the groups gradually increases posteriorly, attaining the number of eight to twelve on the sixth segment, and this number is maintained to the end of the body. Isolated spines are found over the head; over the second, third and fourth segments single ones are still found adjoining the groups of spines, from the fifth onward they are wanting. From here the spines cover the whole free surface of the segments; over the fourth the anterior three-quarters, over the third two-thirds and over the first and second only the anterior half. The stigmata found at the anterior end also serve as distinguishing characters. The parasitic stage appears to last about fourteen days. [Fuller (_Agric. Journ._, Dept. Agric. and Mines, Natal, 1901, iv, p. 606) refers to this as _Bengalia depressa_ also.--F. V. T.] Genus. *Cordylobia*, Grünberg, 1903. *Cordylobia grünbergi*, Dönitz. Syn.: _Ochromyia anthropophaga_, Grünberg, _nec_ Blanch.; _Cordylobia anthropophaga_, Grünberg. Endemic in German East Africa and neighbouring regions. Larva up to 14 mm. long, 4 to 5·5 mm. wide, of cylindrical shape, slightly narrowed behind, truncated, gradually tapering in front; antennæ-like processes, cone-shaped, blunt. Smaller cylindrical formations at the base of the mouth hooks surrounded by a circle of chitinous hooks. Body from the first segment covered with small brown squamous spines which are disposed in numerous irregular transverse rows. The spines are small over the two first segments, the two posterior thirds of all the segments, as well as from the eighth; over the third to the seventh they are larger, but between these there are very small spines. The breathing pores of the stigmata at the anterior end are kidney-shaped; the orifices are elongated and very tortuous, each divided into three. The larval period appears to last several weeks. *Cordylobia anthropophaga*, Grünberg. This well-known cutaneous African parasite seems to have been the cause of much confusion in regard to names. It belongs to the genus Cordylobia of Grünberg, and is one of the family _Muscidæ_, and differs from Auchmeromyia in that the second abdominal segment of the female is of normal size, whilst in Auchmeromyia it is more than half the length of the whole abdomen, and in the male the eyes are holoptic or close together, whilst in Auchmeromyia they are wide apart. The flies of this genus (three so far described) attack man in their larval stage (anyway two of the three), and also dogs and other animals, by burrowing into the skin and producing painful boils. [_C. anthropophaga_, Grünberg, is widely distributed in Africa, extending from Senegal, where its maggot is known as the “ver de Cayor,” and is referred to on p. 590 as _Ochromyia anthropophaga_, E. Blanchard, to Natal, where it is known as the “Natal worm,” and referred to erroneously on p. 591 as _Bengalia depressa_, Walker. [It is a thick-set Muscid of a general straw-yellow colour, with blackish markings on the dorsum of both thorax and abdomen, about 9·5 mm. long. The larva is fat and when mature about 12 mm. long, bluntly pointed in front, truncate behind; from the third to eleventh segments it is thickly covered with minute recurved spines of a brownish colour, arranged in transverse series of groups of two or more, which form more or less distinct irregular transverse rows. On each of the two posterior stigmatic plates, the respiratory slit on either side of the median one is characteristically curved, resembling an inverted note of interrogation. The puparium is brown to ferruginous or black and about 10 mm. long. The maggots are found in both natives and white men, and occur as a severe pest in dogs, also in monkeys, rats, and other mammals. In Sierra Leone it is called the “tumba fly.” The larvæ have been frequently found as true subcutaneous parasites, each larva living singly and forming a boil or warble in the skin, with an opening just as in an ox-warble, through which the maggot breathes and eventually escapes. Although they more usually occur as isolated specimens, Marshall found in Salisbury, South Rhodesia, that sixty were extracted from one lady, and Bérenger-Féraud, in Senegal, that more than 300 occurred in a single spaniel puppy. [Neave (_Bull. Ent. Res._, 1912, iii, p. 217) records it from ulcers in a native at Lourenço Marques in 1908, and at the same time from ulcers in a dog, and that it is a severe pest to man in Mozambique and parts of the Transvaal. It seems to be more abundant in North Rhodesia and Nyasaland than to the north (Neave, _Bull. Ent. Res._, 1912, iii, p. 310). It is also recorded in Zanzibar, German East Africa, Uganda, East Tropical Africa (Neave). [Simpson (_Bull. Ent. Res._, iii, p. 170) records a Muscid larva taken from the breast of a European in South Nigeria that was probably Cordylobia. [It is not known how infection takes place. Neave (_Bull. Ent. Res._, iii, p. 310) says: “Many instances in human beings would preclude the possibility of eggs having been laid direct on the skin: in these cases they have probably been laid on the clothing put out to dry.” [Gedoelst has described another species, _C. rodhani_, and Austen a third species, _C. prægrandis_, from Nyasaland, Cape Colony, Transvaal, Natal, North-west Rhodesia, and German East Africa. [The following are some papers dealing with this subject: _Proc. Ent. Soc._, London, for year 1907, p. xlvii; _Journ. R.A.M.C._, 1908, pp. 5–11, figs. 1 and 2, by Austen; _Journ. R.A.M.C._, 1908, pp. 1 and 2, by Major F. Smith; _Trans. Soc. Trop. Med. and Hyg._, 1910, iii, pp. 223–225, by Austen.--F. V. T.] *Lund’s Larva.* [Illustration: FIG. 411.--Lund’s larva: on the left, the whole larva, magnified six times. On the right, the head end, much enlarged. (After Gedoelst.)] Endemic in the region of the Congo State; called after Commander Lund, from the skin of whose arm it was extracted; 12·5 mm. long, 4·5 mm. broad; colour yellowish, with brown rings, on account of the division of the brown spines; head cone-shaped, with two hemispherical smooth antennæ, two thick black mouth hooks and wart-shaped bodies, between which are situate two to three longitudinal rows of dark brown chitinous laminæ. The body segments are covered over their whole surface with irregularly distributed triangular yellow spines, the points of which are coloured dark brown. Its size increases from the second to the sixth segment, diminishes from the seventh to the ninth, at the tenth it is reduced, and at the eleventh quite small. The posterior stigmata are bean-shaped, each with three markedly tortuous openings. Duration of the larval stage unknown; the same applies to the pupal and imago stages. *Auchmeromyia luteola*, Fabricius. [This fly, the parent of the so-called Congo floor maggot,[416] belongs to a nearly allied Muscid genus to Cordylobia, but which can at once be told by the great length of the second abdominal segment. The maggot occurs in numbers in the native huts in the Congo region and is fairly common in central and northern parts of Mozambique; it is also recorded from the Zambesi River and the vicinity of Barberton in the Eastern Transvaal (_Bull. Ent. Res._, 1912, iii, p. 216), in German East Africa, in Nyasaland, and British East Africa. It is also recorded from Bara, Kordofan,[417] where they occurred on the floor of the men’s prison and bit the prisoners. They were destroyed by sprinkling Jeyes’ fluid on the floor. Neave states (_ibid._, p. 310) that it occurs in the more neglected huts in native villages throughout tropical Africa, and frequently enters a tent when pitched near a village. It is also found in West Africa. The fly is thick-set and about the size and build of a bluebottle fly; length 10 to 12 mm.; tawny in colour to dirty yellowish-brown, with dusky hairs, giving it a smoky appearance; the flattened thorax has long dark stripes and the abdomen a dusky line in the centre of the second segment, which meets a dark line on its posterior border; the dusky third segment has a narrow yellowish anterior line; the fourth segment is also dusky; legs buff with black hairs; the fifth tarsal segment black. The larvæ are whitish, becoming reddish after a feast of blood, with much wrinkled skin and rather flat and broad. They live in crevices of the mud floor, under sleeping mats during the daytime, and come out at night and suck the blood of sleepers and then retire to shelter again. Dutton, Todd, and Christy noticed that where people slept on beds or platforms raised above the floor the maggots were not so numerous as under the sleeping mats laid on the ground. They turned up many of the maggots from a depth of three inches or more.[418]--F. V. T.] [416] Dutton, Todd and Christy, “The Congo Floor Maggot,” _Mem. xiii Liv. Sch. Trop. Med._, p. 40. [417] Balfour, _Journ. Trop. Med_., 1909, xii, No. 4, p. 47. [418] _Journ. Trop. Med._, 1905, viii, No. 6, p. 90. Family. *Oestridæ.* [The family of _Oestridæ_ or warble flies are all parasitic in their larval stage, usually termed the “bot” stage. They are found as parasites in warm-blooded animals, and man is frequently attacked by them. The members of this family have the mouth rudimentary, many of them are hairy and bee-like, with large eyes and the head large, the lower part more or less swollen. The thorax is large with a distinct transverse suture, and the abdomen short and stumpy or very slightly elongated. The male genitalia are hidden, whilst the female ovipositor is often elongated. The wings may be transparent (Hypoderma) or mottled (Gastrophilus), and have muscid-like venation; the tegulæ usually large, the legs moderately long. [As a rule each species is confined to a particular host, but as we see recorded here those that attack animals may also attack man. The flies occur in warm weather and usually during the warmest part of the day, and have a strong dislike to shade and water. The genus Hypoderma attack oxen, sheep, goats, antelope and musk deer; Oestrus, sheep, antelope and horses; Gastrophilus, the horse and ass; Cephenomyia, the deer; Cepholomyia, the camel and buffalo; Dermatobia, dogs, cats, oxen, deer, apes and man; Cuterebra and Rogenhofera, rodents and opossums. [Some live as parasites in the stomach and intestines (Gastrophilus); others infest the skin (Hypoderma, Dermatobia and Oestromyia, the latter on _Lagomys_ and _Hypodæus_); _Œdemagena tarandi_ also infests the skin of the reindeer in Siberia and boreal America. Oestrus lives in the nasal sinus, and Cephalomyia in the throat as well, Cuterebra and Rogenhofera, the skin or scrotum, so that we have really three groups of parasitic oestride larvæ: (i) cutaneous, (ii) intestinal, and (iii) facial. [No species seems confined to man, but the so-called “creeping disease,” caused by Hypodermæ, and the attack of sheep nasal fly are comparatively common, as also is the Dermatobia attack.--F. V. T.]. CUTANEOUS OESTRIDÆ. The eggs are deposited on the surface of the body; the larvæ burrow in the skin, which they reach after somewhat long peregrination. Genus. *Hypoderma*, Latreille. *Hypoderma bovis*, de Geer. The cattle fly or warble fly, which swarms during the hot season, settles on the head or on the hair of grazing cattle: through the young being licked off they gain access to the mouth and are swallowed.[419] The larvæ appear first in the commencing portion of the stomach, to escape, as some state, into the preceding sections of the alimentary canal; at any rate, they are found from July onward regularly in the submucous tissue of the pharynx, in which they travel about for several months (up to November, and in isolated cases up to February); they then penetrate the muscularis and migrate by way of the subserosa along the mediastinum, the crura of the diaphragm, the renal capsules, and the intermuscular connective tissue of the psoas muscle in the direction of the spinal canal, into which they penetrate by way of the muscles and nerves, through the intervertebral foramina. Here they stay for about two to three months, then they leave the spinal canal again through the vertebral foramina and make their way (from January to March) through the intermuscular connective tissue of the muscles of the back to the skin of the back, where sooner or later (from January to June) they arrive and enter a resting stage, which commences with penetration of the skin and terminates with outward migration from the boils due to the wound set up by the maggot. At the commencement of this period the larvæ cast their skin, and their form, hitherto cylindrical, becomes oval. After about a month, a second moulting of the skin takes place--the third larval stage, which lasts about two and a half months (up to June). The approaching end of the same is indicated by a change of colour on the part of the larva from the hitherto yellowish-white to brown and finally to blackish-brown. When they have become mature the larvæ leave the warbles, drop on to the ground and pass into the pupal stage in the superficial layers of the soil within twelve to thirty-six hours. After about a month the flies emerge. Irregularities with regard to the time and direction of the migrations of the larvæ take place (Jost, H., in _Zeitschr. f. wiss. Zool._, 1907, xxxvi, p. 644). [419] [This is not the case, for Carpenter has shown that muzzled calves become infected (“Mém. First Int. Cong. Ent.,” pp. 289–293). Jost (_Zeitschr. f. wiss. Zool._, 1907, xxxvi, pp. 644–715) thinks that the ova, not young larvæ, are ingested (vide note in Supplement).--F. V. T.] In a number of cases the larva of the cattle fly has been observed in the human integument, usually in the winter months, that is, during the migration period; consequently, it is not surprising that the larvæ before they enter on the resting stage and produce a warble undergo migrations. But that this takes place subcutaneously--which does not appear to be so in the case of cattle--is perhaps explained by the fact that in man, on account of the short space that has to be traversed, the larvæ are not sufficiently developed to enter on the resting stage simultaneously upon having obtained access to the integument. Whether the Oestrid larvæ in Bulgaria that similarly migrate beneath the skin in man belong to the cattle fly or to another species, or even another genus, has not yet been ascertained. (Doctorow, in _Arch. de Par._, 1906, x, p. 309; Spring, A., in _Bull. Acad. sci. Belg._, 1861 (2), iv, p. 172; Walker, R., in _Brit. Med. Journ._, 1870, i, p. 151; Kjelgaard, in _Ugeskr. f. Laeger_, 1904, p. 535; Condorelli, M., in _Bull. Soc. Zool. Ital._, 1904, xiii, p. 171.) *Hypoderma lineata*, de Villers. The larvæ of this species, that occurs not only in Europe but in North America, live under similar conditions in the skin, very rarely in man; also migrating subcutaneously (Topsent in _Arch. de Par._, 1901, iv, p. 609). [In Sweden, the ox warble fly (_H. bovis_) is well known to attack man. Schoyen states “that over 100 years ago up to the present time cases of travelling grubs under the human skin in some districts of Sweden were well known.” The species appeared to be _H. bovis_, many of which he had examined. They accomplished long ramblings under the skin, always in an upward direction, previous to their appearance through an opening in a tumour on the upper part of the body, on the head, neck, or shoulders. An interesting case is recorded in _Insect Life_, ii, pp. 238–239. A bot similar to _H. diana_ was taken from the eye and cheek of a child at Kane, McKean County, Pa., U.S.A. It was said to have travelled in five months from the elbow to the eye. Riley later (_Insect Life_, iv, p. 310) was inclined to think the maggot was that of _H. lineata_, the common American ox warble, which is also found in Europe in great numbers. I have recorded another case in England (_Rept. Econ. Zool._ for year ending September 30, 1910, p. 128), where Dr. Menzies removed the larva of _H. bovis_ from the upper eyelid of a patient. It caused considerable swelling of the face, much pain and distress; but the case did well, and the wound healed at once. The larva was nearly mature. Numerous other references to this so-called creeping disease will be found in the Supplement. [It is quite probable that _bovis_ and _lineata_ are confused in the latter accounts. The larvæ are, however, easily distinguished if carefully examined.--F. V. T.] *Hypoderma diana*, Brauer. In its larval stage it lives like other species of Hypoderma, attacking the red deer (_Cervas elaphas_) and roe deer (_Cervas capreolus_); it is occasionally also found in man (Joseph, in “Myiasis externa dermatosa,” Hamburg, 1800; Völkel, in _Berl. klin. Wochenschr._, 1883, xx, p. 209). Genus. *Dermatobia*, Brauer. *Dermatobia cyaniventris*, Macq. Syn.: _Dermatobia noxialis_, J. Goudot. The genus Dermatobia represents the subcutaneous _Oestridæ_ of Europe in warmer parts of America. Both domesticated and wild mammals are attacked, according to one statement birds also (_Ramphastus_), and man with fair frequency.[420] It is assumed that in all cases one and the same species is concerned, for which recently a name originating from C. Linné, jun. (_Oestrus hominis_), has been employed. Three larval stages are recognized in the skin; the two first appear to resemble one another in the club-shaped or tadpole-like appearance (called macaque in Cayenne, mayacuil [mayoquil] in Mexico), the third is swollen spindle-shaped (Berne, called torcel). Segments 2 to 4 in the club-shaped larvæ are closely beset with small black spines, segments 5 to 7 bear at the anterior border a complete ring of strong black hooks, segments 4 to 6 a similar ring, which, however, is interrupted at the ventral surface. The four last segments forming the tail are smooth, only at the posterior end are there small spines. The arrangement of spines of the third stage differs from this. Italian workmen that have been employed in Brazil show the presence of Dermatobia larvæ on their return (Blanchard, in _Bull. Soc. Ent. France_, 1893, p. 24; _Bull. Soc. centr. de Méd. vet._, 1896; _Ann. Soc. Ent. France_, 1894, lxiii, p. 142; Ward, H. B., in Mark Annivers. Vol., Article 25, p. 483, New York, 1903). [420] Duprey advances the opinion that Dermatobia deposits its eggs not only on the skin of man and animals, but also on the leaves and twigs in the bush, where, too, young larvæ have been met with which gain access from hence to men and animals (_Journ. Trop. Med. and Hyg._, 1906). [Illustration: FIG. 412.--_Dermatobia noxialis_, Goudot.] [Illustration: FIG. 413.--Larva of _Dermatobia cyaniventris_ in its natural size and magnified. (After Blanchard.)] [Illustration: FIG. 414.--Larva of _Dermatobia cyaniventris_. Enlarged. (After Blanchard.)] [_Dermatobia cyaniventris_, Macquart, 1843, is said not to be the same as _noxialis_ (_vide_ Brauer, “Mono. Oestriden,” 1863, p. 266). It is known by various other names, as nuche or gusano in New Granada, the ura in Brazil, and the macaw fly in Cayenne. It occurs in Central and South America and the West Indies. According to Goudot the fly is found in great numbers on the borders of large woods and lands covered with underwood. [It is seldom that more than one larva is found in each individual. It is generally found in the arm and leg, but now and then the face. The perfect insect has never been bred from a larva removed from a human being, so that there is still uncertainty as to the actual species. _D. cyaniventris_ is 11 to 12 mm. long, has an ochraceous buff-coloured face, dark grey thorax, metallic dark blue to purple abdomen, and brownish wings. _D. noxialis_ is somewhat larger. [In the _Journal of Tropical Medicine and Hygiene_, January 15, 1905, viii, p. 23, reference is made to this Oestrid in Trinidad, where it is called the “mosquito worm.” One case here recorded showed no fewer than four worms on the chin and one on the hand. It is here stated that the fly never attacks man or animals directly, as it is said to do by Scheube, but that the eggs are deposited on leaves and branches in wooded lands and forests, and thus man, hunting dogs and wild animals in passing through get the larvæ deposited on them accidentally. The affection is common in Trinidad. Mention is made that a little 1 in 40 carbolic lotion syringed into the aperture in the skin over the worm quickly killed it. [The cattle worm, or founzaia ngómbe, is the name given to a larva which develops beneath the skin of oxen and men in Central Africa, especially amongst the natives and stock of Unyamonezi. According to P. Dutrieux, the egg is laid by a large fly that accompanies cattle. It is unknown between the central plateau or the Ugogo and the East Coast.--F. V. T.] CAVICOLOUS OESTRIDÆ. The forms belonging to this group inhabit as larvæ the nasal and frontal sinuses of ruminants, _Equidæ_ and _Proboscidæ_, which they leave for the pupal stage. The larva of-- Genus. *Oestrus*, Linnæus, *Oestrus* (*Cephalomyia*) *ovis*, L., occurring in sheep, has also been observed in man in six cases in the nose and larynx (Saitta in _Gaz. d. Osp. d. Clinic_, 1903, No. 128). So far as is known, the eggs are deposited in the nasal cavity. [_Oestrus ovis_ frequently occurs in man. MM. Sergent (_Ann. de l’Inst. Pasteur_, 1907, pp. 392–399) mention that they lay their ova on the noses, eyes and mouth of humans in Algeria whilst flying, but that they disappear after three to ten days or the inflammation produced by them. Portschinsky (_Mem. Bur. Ent. Sci. Com. Cent. Bd. Land Adm. and Agric._, 1913, x, No. 3, p. 63) also gives cases. He doubts that ova are laid on the nose; evidently the Russian habit is anomalous, for the Sergents, Collings and myself find ova laid as a common occurrence. I have often seen them on the nose of sheep. This fly also occurs in the Argentine (Serres, in _Gaceta Rural_, April, 1913, vi, pp. 759–761). [The tamné or thimni of the Kabyles, a human myiasis of the Tuareg mountains in the Sahara, is caused by _Oestrus ovis_. Here the larvæ are said to be ejected on to the conjunctival and nasal mucous membrane of humans. [Ed. and Lt. Sergent (_Bull. Soc. Path. exot._, 1913, vi, No. 7, pp. 487–488) report their attack from the Ahaggar mountains, in Central Sahara. The Tuareg name for the fly, tamné, is the Targui form of the word thimni used by the Kabyles.--F. V. T.] GASTRICOLOUS OESTRIDÆ. The eggs are deposited on the hairs of _Equidæ_, and the larvæ escaping from them are licked up and swallowed. They pass their larval stage, according to the species, in various parts of the intestine and stomach, and when mature, pass out _per anum_ in order to undergo the pupal stage. Genus. *Gastrophilus*, Leach. One of the most frequent species is _Gastrophilus equi_, Fabr.; the eggs are laid on the hairs; the larvæ live some ten months in the stomach, living attached to the inner surface. The eggs of _G. hæmorrhoidalis_, L., are deposited on the lips or the long hairs on them. The larvæ adhere to the cardiac end of the stomach, to the stomach itself, and finally to the terminal portion of the intestine. Here, however, and elsewhere in the intestine, the larvæ of _G. pecorum_, Fabr., are also met with, whilst the larvæ of _G. nasalis_ (so called because the eggs are deposited in the nasal orifices) almost exclusively inhabit the anterior section of the duodenum. Cholodkowsky attributes the “wormlet” observed by Samson and Sokolew (_Wratsch_, 1895, Nos. 48 and 57) and others (_ibid._, 1896–98) to _Gastrophilus_ larvæ. It burrows into the epidermis of man by minute passages. This observation should, however, be verified. The phenomenon is designated as skin-mole, larva migrans, and creeping eruption. OTHER PAPERS ON DIPTEROUS LARVÆ, ETC., IN MAN. (1) “Ein Fall von lebenden Fliegenlarven im menschlichen Magen,” _Deutsch med. Wochenschr._, Leipz. and Berl., xxiv (12), pp. 193–194. Bachmann, and review of same, “Living Fly Larvæ in the Human Stomach,” _Philadelphia Med. Journ._, 1898, i, 18, p. 773. (2) “Sudi una larva di dittero parassita della congiuntiva umana,” _Ann. di ottal._, Paira, 1895, xxiv (4), pp. 329–336, 1 fig., E. Baquis. (3) “Sur quelques diptères suceurs de sang, observé à Terre-Neuve,” _Arch. de Par._, Paris, 1900, iii (1), pp. 202–204, E. Barret. (4) “An Account of the Larvæ of two Species of Insects discharged from the Human Body,” _Edin. Med. and Surg. Journ._, January 1, 1811, vii (25), pp. 41–48, 1 pl., figs. 1 to 8, T. Bateman. (5) “Un cas de myiase par la _Sarcophaga magnifica_ en Roumanie,” _Bull. Soc. Zool. de France_, Par., 1891, xvi (2), pp. 25–26, R. Blanchard. (6) “Sur les oestrides américains dont la larve vit dans la peau de l’homme,” _Ann. Soc. ent. de France_, 1892, v, pp. 109–154, figs. 1–12, R. Blanchard. (7) “Note additionnelle sur les oestrides américans dont la larve vit dans la peau de l’homme,” _Bull. Soc. ent. de France_, Paris, 1894, xiv, pp. 209–211, R. Blanchard. (8) “Note sur des larves de Dermatobia provenant de Brésil,” _Bull. Soc. ent. de France_, Paris, 1893 (2), pp. 24–27, R. Blanchard. (9) “Larven der Wohlfahrtfliege (_Sarcophila wolfahrtii_) im Zahnfleische eines Menchen,” _Wratsch._, St. Petersburg, 1888, 5–6, E. K. Brandt. (10) “Ueber den sogenannten _Oestrus hominis_ und die oftmals besichteten Verirrungen von Oestriden der Säugetheiere zum Menchen,” _Verhandl. d. k. zool.-bot. Gesellsch._, 1860, x Abhandl., pp. 57–72, Brauer. (11) “Ueber die Larven der Gattung Cuterebra, Clk.,” _Verhandl. d. k. zool.-bot. Gesellsch._, 1860, x Abhand., pp. 777–786, Brauer. (12) “Des désordres produits chez l’homme par les larves de la _Lucilia hominivorax_,” _Thèse_, Paris, 1864, 43 pp., V. Audouit. (13) “Note on the ‘Flesh Worm,’” _Med. Press and Circ._, London, April 12, 1882, lxxxii (N.S. xxxiii), p. 314, P. S. Abraham. (14) “Larvas de la _Calliphora limensis_ en fosas nasalis,” 1855, 18 pp., F. Aguirre. (15) “Raro caso di parasitismo nell ’uomo dovuto alla larva di una mosca (_Sarcophaga affinis_, Meigen),” _Boll. d. Soc. Rom. per gli Stud. Zool._, Roma, 1893, iv (5–6), pp. 278–289, 1 pl., 3 figs., Giulo Alessandrini. (16) “Observations sur l’espèce de ver nommé Macaque (Oestrus),” _Mém. Acad. Sci. par Hist._, 1753, p. 72, F. Artur. (17) “Contribuição ao estudo da biologia da _Dermatobia cyaniventris_,” _Trav. do Inst. de Manguinhos_, 1908. BITING-MOUTHED AND OTHER NOXIOUS DIPTERA WHICH MAY BE DISEASE CARRIERS. [Amongst the division _Brachycera_ (as meant in this work) we get several groups of flies which, like the fleas and mosquitoes, are partially parasitic on man, the adults, mainly in the female sex, being provided with a piercing mouth with which they extract the blood of man and animals. The importance of these parasites is not the mere fact that they feed upon our blood, but that they often carry germs from man to man (tsetse-flies and trypanosomiasis, _Tabanidæ_ and anthrax). Amongst the most important biting-mouthed _Diptera_ in this section are the following: _Tabanidæ_, or gad-flies; _Glossinæ_, or tsetse-flies; and certain other _Muscidæ_. Some of the exotic _Asilidæ_ and a few _Leptidæ_ also bite man. Family. *Tabanidæ* (Gad-flies). [The _Tabanidæ_ have a broad, rather flattened body and a large head; eyes united in the male (except in some Chrysops). The antennæ are composed of three segments, have the third joint composed of five to eight annuli--in Chrysops they are fairly long. The proboscis is projecting, and sometimes much elongated. The legs are moderately stout. The venation of the wings is shown in fig. 415. [This family of gad or horse flies contains a great number of genera, all of which may bite animals and man more or less severely. The female alone is blood-sucking, the males feed upon the juices of flowers. The females deposit their spindle-shaped white, black, or brown eggs on leaves, stems of plants that either overhang or stand in water, and amongst rushes; they are at first white, but become brown or black. The eggs are laid in rounded, flattened or conical masses composed of layers one upon the other. The larvæ are carnivorous, feeding upon snails, worms, other larvæ, etc., and have a distinct head; they are cylindrical, composed of eleven segments, the last with a vertical breathing pore, or the last two segments may form a breathing tube. The majority taper to a point at each end, in colour shining white or dull grey to yellowish, many of the larger specimens mottled or banded with dark brown or black. The first seven abdominal segments are encircled near the anterior margin with a ring of fleshy protuberances consisting of a transverse dorsal ridge which may be divided by a depression into two. The young larvæ burrow into any soft vegetable substance; they live both in the water and under damp soil surrounding water, also in damp earth generally. The larvæ are not only carnivorous, but they are cannibals, frequently devouring their own species. They may take more than a year to mature. [The pupæ are found close to the surface of mud and earth, and are mostly dull yellowish to brown in colour, with rows of spines on the distal third of each abdominal segment; the thorax bears a pair of ear-shaped spiracular structures, and there are also six denticles at the apex of the abdomen. [A habit common to the adults of most of the _Tabanidæ_ of considerable economic importance is that of the adults coming to water to drink. Portschinsky[421] has found that by applying kerosene to the pool they frequent the adults are killed, and Hine[422] that the same oil kills the larvæ that fall into the water from eggs laid on plants above. [421] _Vide Bull._ 20, _N. Sc., U.S. Div. Ent._ [422] “_Tabanidæ_ of Ohio,” _Ohio State University Bull._ 19, 1903, sec. 7, p. 14. [_Tabanidæ_ are not only of importance as purely biting insects, for they may often convey pathogenic organisms from one animal to another, such as the bacillus of anthrax, which they are known to carry, and possibly also trypanosomes in regard to man. Chrysops also acts as a host of _Filaria loa_ in South Nigeria (Leiper, _Brit. Med. Journ._, January, 1912, pp. 39–40). Two species are incriminated, _viz._, _C. silacea_ and _C. dimidiata_. With animals these flies play a more important part, for MM. Sergent, in Algeria, have proved that species of Tabanus are able to transmit three forms of animal trypanosomes by biting a healthy animal as long as twenty-two hours after having bitten an unhealthy one. In India they have also been shown to transmit the parasite of “surra” in dogs and rabbits by Rogers. Other observers have since corroborated these results, and Mitzmain, who has recently performed valuable work in this connection, states that _T. striatus_ is undoubtedly the carrier of this disease in the Philippine Islands. Certain members of the genus Hæmatopota have also been shown to be capable of the direct transmission of _Trypanosoma evansi._ Martoglio (_Ann. d’Ig. sper._, 1913, xxiii, N.S., No. 3, pp. 363–366) states that the trypanosome disease of dromedaries known as salaf is transmitted by _Tabanidæ_, especially Pangonia (_P. magretti_ and _P. beckeri_) in Italian Somaliland. It is quite likely that these flies play a much greater part in the spread of such diseases than is imagined at the present time. [Illustration: FIG. 415.--The ox gad fly (_Tabanus bovinus_, Linn.).] [The _Tabanidæ_ are divided into two groups or subfamilies: (1) The _Pangoninæ_, and (2) the _Tabaninæ_; the former have spurs on the hind tibiæ and usually ocelli; the latter have neither tibial spurs nor ocelli. [The _Pangoninæ_ contain two main genera, Pangonia and Chrysops. In the former the proboscis is much elongated, and the third antennal segment is composed of eight rings, and is never angulated or ungulated at the base. The proboscis is often very long. [In Chrysops, the so-called blinding storm flies, all the three segments of the antennæ are long, the third having only five annulations, and the proboscis short but very strong. [There are many genera in the _Tabaninæ_, which are found in all parts of the world, of which two only are shown here--_viz._, Tabanus and Hæmatopota. The former has the first two segments of the antennæ short, the third angulated at the base, sometimes spurred and composed of five annulations; the second has the second segment short, and the third composed of four annulations--never angulated nor spurred at the base--and the wings are adorned with grey or brown markings. These latter are usually called “brimps” and “clegs” in Britain, the former gad or horse flies, the seruts and mangrove flies of tropical countries. [Illustration: FIG. 416.--The brimp (_Hæmatopota pluvialis_, Linn.).] Family. *Asilidæ* (Wolf Flies). [These flies are of little importance in regard to the subject dealt with in this book; but I have notes sent concerning the biting habits of one or more species belonging to this family from the Malay States and Africa. [_Asilidæ_, or wolf flies, are easily told by the following characters: Large or moderate-sized flies, thickly hairy; head separated from thorax by a narrow neck; eyes separated in both sexes; proboscis firm and horny, adapted for piercing; abdomen long, pointed, and composed of eight segments. Legs strong and bristly, of moderate length. Wings sometimes mottled, lying parallel over the abdomen when at rest. There are nearly 3,000 species. They live mostly upon insects, but some are said to bite animals and man. They are, however, of little importance in this respect. Family. *Leptidæ.* [This widely distributed family of flies has a few species which suck the blood of man, and the writer has been personally badly bitten in Norway by a Leptis which was apparently _Leptis scolopacea_. [The _Leptidæ_ have usually blotched wings and similar venation to Tabanus; they are elongated flies of moderate or large size, and of dull colours. The antennæ are varied and consist of three segments, either with or without a terminal bristle or with the third segment compound, and in a few they may be almost nematocerous. The wing veins are distinct, very crowded anteriorly, the third long vein is furcate, basal cells large, and there are usually five posterior cells, the anal cell being open in some; the squamæ are always small, sometimes only rudimentary. [Four are known to be blood-suckers, namely the American Symphoromyia, _Trichopalpus obscurus_ in Chili, and _Leptis strigosa_ and _L. scolopacea_ in Europe. The genus Symphoromyia has a single spur on the hind tibiæ, none on the fore or mid tibiæ, the third segment of the three-ringed antennæ kidney-shaped, and a short proboscis. In the genus Leptis the hind tibiæ have two spurs, and the third antennal segment is not reniform. [The other biting genus Trichopalpus can be told at once by the elongated proboscis. Most of this family live upon other insects. The larvæ live in earth, decaying wood, sand, stagnant waters, and the nests of wood-boring beetles; they are usually cylindrical and may have fleshy abdominal legs; the anal segment has a transverse cleft, and often two posteriorly directed processes and two stigmata between them. They are all predaceous, and in one genus (Vermileo) make pitfalls in sand like the ant lions (_Myrmeleon_). Blood-sucking Muscidæ. [The blood-sucking _Muscidæ_ are mainly contained in the following genera: Glossina, Stomoxys, Hæmatobia, Lyperosia, Stygeromyia, Philæmatomyia and Bdellolarynx. [The first is the most important genus on account of the part it plays in the spread of trypanosome diseases. Stomoxys may also serve as a disease carrier. The remainder and a few more genera cause considerable annoyance by their bites, and may also act as occasional carriers of pathogenic organisms. All these flies have their mouth parts elongated to some extent, forming a distinct proboscis, which becomes more or less strongly chitinized; the labella are usually serrated or spiny, and thus form a structure easily capable of piercing the skin. Unlike the _Culicidæ_, the blood-sucking _Muscidæ_ have the sanguinary habit common to both sexes. Genus. *Glossina*, Westwood. [This genus contains sixteen species,[423] all of which are confined to the Ethiopian region. Glossina may be distinguished from other allied genera by the proboscis, the antennæ, wings, and male genitalia. The proboscis projects forwards and has a swollen bulb-like base to the slender labium which holds the two structures, the needle-like epipharynx and the thread-like hypopharynx; the whole proboscis is ensheathed in the maxillary palpi. The antennæ have the first two segments small, the third large with a marked pore, the orifice of the sense organ near the base; from the base of the third segment also arises the three-jointed arista, the first two segments being, however, minute; the third bears a series of from seventeen to twenty-one fine branched hairs on one side. The male genitalia or hypopygium is more or less oval and tumid, its long axis lying in the antero-posterior direction, with a vulviform median groove (the anus) running from the anterior margin to beyond the middle. [423] This does not include _G. maculata_, Newstead, which is regarded by Austen as a synonym of _G. palpalis_, Rob. Des.; according to this authority the curiously spotted appearance of the type and only example of _G. maculata_ is due to foreign matter. [Newstead has shown the importance of the study of the genitalia in separating species (_vide_ _Bull. Ent. Res._, ii, pp. 9–36 and 107–110, and iii, pp. 355–360; and _Ann. Trop. Med. and Par._, vii, No. 2, pp. 331–334). [Illustration: FIG. 417.--Head of _Glossina longipalpis_, Wied. (After Grünberg.)] [Illustration: FIG. 418.--Antenna of _Glossina pallidipes_, male. (After Austen.)] [The tsetse-flies reproduce differently from all other _Muscidæ_. The female produces at each birth a single full-grown larva, which is retained within the oviduct and there nourished by the secretion of special glands, and on being born crawls to some hiding place and at once becomes a puparium. [The larva is a yellowish footless maggot nearly as large as the mother’s body, the skin shagreened and the anal extremity having a pair of large, black, granular prominences separated by a depression containing the breathing pores. [The puparium is brown of various shades, the tumid lips of the larva being conspicuous, the size and shape of the lips enabling the puparia to be identified. [These puparia are often found in masses at the base of trees, in hollows in trees and rocks just buried under vegetal debris. These insects are generally confined to definite tracts known as “fly-belts.” They usually occur in damp, hot places on the borders of rivers and lakes, and never far from water in the case of the _palpalis_ group, although others of the _morsitans_ group may be found a considerable distance from water. They are usually absent on grass plains, but may now and then occur there (Kinghorn, _vide_ Hindles’ “Flies and Disease, Blood-sucking Flies,” 1914, p. 274); cover of trees, shrubs, or thick reeds is essential to them. [Their range in Africa extends roughly from 18° N. to 31° S. [_Glossina palpalis_ is the chief carrier of the more prevalent type of sleeping sickness. Two distinct types of parasites can produce this disease, _viz._, _Trypanosoma gambiense_, which produces the ordinary sleeping sickness, transmitted by _G. palpalis_, and _Trypanosoma rhodesiense_ the Rhodesian or Nyasaland sleeping sickness, transmitted by _G. morsitans_, and possibly identical with _T. brucei_, the parasite of N’agana. Koch has also shown that _G. pallidipes_, Austen, and _G. fusca_, Walker, can be artificially infected with the human trypanosome. It appears probable that Koch used _G. brevipalpis_, not _G. fusca_, in his transmission experiments, as at that time fusca included nearly all the large tsetses, but _brevipalpis_ is its Eastern representative. [A TABLE OF SPECIES (modified after Austen) is appended here:-- I. _Glossina palpalis_ GROUP.