44 2 THE ANIMAL PARASITES OF MAN 



develops beneath the skin of oxen and men in Central Africa, especially amongst 

 the natives and stock of Unyamoriezi. According to P. Dutrieux, 1 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.] 



Biting-mouthed Brachycera. 

 By F. V. Theobald. 



[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 in all probability often carry germs from man to man (Tsetse flies and 

 Trypanosomosis, Tabanidae and Anthrax). Amongst the most important biting- 

 mouthed diptera in this section are the following : Tabanidce, or Gad Flies, 

 Glossince, or Tsetse flies ; and certain other Muscidce. Some of the exotic 

 Asilidce and a few Leptidce also bite man. 



Family Tabanidce or Gad Flies. 



The Tabanidae have a broad, rather flattened body and a large head ; 

 eyes united in the male. The antennae have the third joint composed of 

 five to eight annuli. The proboscis is projecting, and sometimes much 

 elongated. The legs are moderately stout. The venation of the wings is 

 shown in the figure 287. 



This family of Gad, or Horse flies, contains a great number of genera, all 

 of which 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 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 convex masses com- 

 posed of layers one upon the other. The larvae are carnivorous, feeding 

 upon snails, other larvae, &c., and have a distinct head ; they are com- 

 posed 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, many of the 

 larger specimens banded with dark brown or black. The young larvae 

 burrow into any soft substance, animal or vegetable ; they live both in 

 the water and under damp soil surrounding water, also in damp earth 

 generally. The larvae are not only carnivorous, but they are cannibals, 

 frequently devouring their own species. They may take more than a 

 year to mature. 



The pupae are found close to the surface of mud and earth, and are 

 mostly dull yellowish in colour with rows of spines at the apical third of 



1 " Apercu de la pathologic des Europeans dans I'Afrique intertropicalc," ThZse de 

 Paris, p. 60, 1885. 



