356 



THE INSECTS 



arista, long palps, a bulb to the proboscis and a characteristic upbending of the 

 fourth longitudinal vein to meet the midcross vein. The female deposits her larva 

 near a shady place upon loose, dry, sandy soil. Moisture and sunlight are not favor- 

 able for pupal development, the sun being particularly injurious, so that pupae, 

 buried only an inch deep and away from shade, are killed. This fact has been 

 utilized in prophylaxis by cutting down the trees. The trouble is that the bush 

 growth which soon follows is favorable as shade for the pupae. 



The female gives birth to a single, yellowish brown, motile larva, which is almost as 

 large as the mother and which, upon reaching the ground, bores its way into a coarse, 

 sandy soil for a depth of about 2 inches and then becomes a pupa. The larval stage 



FIG. 87. Insects in which the adult stage is important, (i) Stomoxys calcitrans; 

 (2) S. calcitrans, larva; (3) Tabanus bovinus; (4) Tabanus larva; (5) Glossina palpalis; 

 (6) G. palpalis, side view; (7) G. palpalis pupa; (8) Glossina palps and arista. 



in the mother lasts about two weeks and the pupal stage in the ground about a 

 month, 



Male and female flies bite and transmit the disease. They bite in the daytime, 

 usually from 9 A.M. to 4 P.M., and will bite in the sunlight. 



With a view to eradication of the disease certain areas have been depopulated, but 

 upon examining the flies caught in the district a year or more later, infected flies 

 have been obtained. This would indicate some other reservoir than man. It is 

 now generally conceded that the trypanosome strain in the antelope is the same as 

 T. rhodesiense, both being transmitted by G. morsitans. Taute however believes them 

 different as he not only injected blood containing such trypanosomes into himself, 



