[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.]

[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.].

The eggs are deposited on the surface of the body; the larvæ burrow in the skin, which they reach after somewhat long peregrination.

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).

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.]

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).

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).

[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.]

[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.]

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.

[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.

[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. Portschinsky421 has found that by applying kerosene to the pool they frequent the adults are killed, and Hine422 that the same oil kills the larvæ that fall into the water from eggs laid on plants above.

[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.

[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.

[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).

[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.

[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.

[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).

[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:—

[This is the chief carrier of sleeping sickness in Nature. It is found in places over the whole of West Africa from the mouth of the Senegal River to Angola, and extends eastwards into the Bahr-el-Ghazal. The eastern boundary follows the valley of the Nile and includes the eastern shores of Lakes Victoria and Tanganyika; from the southern end of the lake the boundary tends south-west, approximately following the frontier between North-eastern Rhodesia and the Congo Free State, and passing through the Katanga district of the latter country into Angola (Austen). It may occur up to 3,000 ft.; but, according to Bagshawe, it has not been recorded above 4,000 ft. It feeds on the blood of many animals, including reptiles, amphibia, birds, and even amphibious fishes, as well as all the wild mammals. It seems, however, to possess a decided predilection for man, and undoubtedly thrives better upon mammals and birds than upon cold-blooded animals.

[It is not usually found far from water, requiring a humid atmosphere and temperature of about 85° F. (shade). But a marked seasonal distribution is shown, the flies considerably extending their range during the rainy season, and thus visiting districts which are dry for the greater part of the year; as the rains diminish the fly gradually leaves the temporary haunts and returns to the more permanent ones. It bites only by day, and then only in sunny weather, and usually lives in shade.

[Roubaud has shown that the first larva produced is about three weeks after copulation, and that others are produced at an interval of nine or ten days. The puparium stage is rapidly produced after the expulsion of the larva, often in three-quarters of an hour. The puparium stage lasts from thirty-two to thirty-five days. The puparia occur in well-drained humus close to water, sheltered by trees or bushes, in crevices in rocks, and between the exposed roots of trees, sometimes in sand.

[Bruce has shown that only a very small percentage of flies fed experimentally on infected animals ultimately become infective, and that the infectivity of this small percentage depends upon a delayed infection of the salivary glands.

[A variety, wellmani of Austen, is found in Angola, Gambia, the Katanga district of the Congo Free State, the Matondwi Islands of Tanganyika, etc.

[This species has been shown by Kinghorn and Yorke, and also by Bruce, to be responsible for the transmission of Trypanosoma rhodesiense, the micro-organism producing sleeping sickness in man in Rhodesia and Nyasaland and also in parts of German and Portuguese East Africa. Fisher and Taute have demonstrated experimentally that Trypanosoma gambiense—the sleeping sickness parasite of other parts of Africa—may also be transmitted by this fly, and in addition it is known to be capable of disseminating several species of trypanosomes pathogenic to animals. Of these, T. brucei (=? T. rhodesiense), the parasite of tsetse disease, first incriminated by Bruce, is perhaps the most important.

[It is the most widely spread of all tsetse-flies; its range extends from Senegambia in the north-west to Southern Kordofan and Southern Abyssinia in the north-east, and then southwards to the Bechuanaland Protectorate, North-eastern Transvaal and Zululand. The actual localities given by Austen are Gambia, French Guinea, Gold Coast, Togoland, Dahomey, Northern Nigeria, Congo Free State, the Bahr-el-Ghazal, the Uganda Protectorate, German East Africa, and Portuguese East Africa.

[This species is confined to “belts,” often of very limited extent, and appears to prefer regions where there is sufficient vegetation for moderate but not excessive cover and a hot, moderately dry climate. It is not nearly so dependent upon water as is G. palpalis, and generally is most active in a dry atmosphere; some observers, however, state that in certain districts it is more common along the banks and edges of rivers. This tsetse-fly has been taken as high as 5,500 ft. altitude. It infests native villages as well as the bush. Like other tsetse-flies it bites not only during the hottest part of the day, but also on bright warm moonlight nights, and it feeds on the blood of all mammals.

[The structure of the male genitalia of those representatives of G. morsitans occurring on the West Coast of Africa and in parts of the Soudan presents certain constant differences from that of the typical form of this species; this form is known as G. morsitans, race submorsitans, Newst.