XVl] GLOSSINA TACHINOIDES 255 



palpalis is usually quiescent. Moreover, according to Dr 

 Alexander the flies bite after dark, at 7.0 p.m. he having had 

 to take refuge in his mosquito net, and his boys remarked that 

 the flies were more troublesome than mosquitoes. 



G. tachinoides is very resistant to heat, an exposure of one 

 and a half hours in a stove at 40° C. being well borne. As a 

 result the species is able to exist in very warm regions and 

 occurs in the Sudan in localities that are too hot for G. palpalis. 



Reproduction. The flies copulate immediately after hatch- 

 ing and at 25° C. the larvae are deposited at intervals of about 

 eight days. The duration of the pupal stage in Dahomey (at 

 24° to 25° C.) was found by Roubaud to be from 28 to 35 days. 



Like palpalis, the pupae will resist immersion in water for 

 a period of 20 hours, and are able to withstand a tempera- 

 ture of 35° C. for ten hours in the day, so long as the experiment 

 is only continued for a few days ; if it goes on for a month, all 

 the pupae die. 



G. Tachinoides and Disease. 



This species is one of the main carriers of Souma {T. cazalhoui) 

 and T. dimorphon, in West Africa. Moreover, although direct 

 experimental evidence is lacking, it is likely that tachinoides 

 is able to transmit sleeping sickness. In Togoland on the 

 Oti River, a tributary of the Volta, Zupitza believes that it 

 takes the place of G. palpalis as a carrier of this disease. 



Prophylaxis. The methods that will be described for 

 G. palpalis (see p. 315) are also applicable to tachinoides, and 

 in Northern Nigeria experiments have been made on the effect 

 of cutting down the undergrowth on the banks of rivers. One 

 month after the clearing very few tachinoides could be found 

 and pupae were sought without success. 



LITERATURE. 



Carter, R. Markham (1906). Brit. Med. Journ. Nov. 17, 1906, p. 1393. 



Moiser, B. (1912). Bull. Ent. Research, vol. iii. p. 195. 



Neave, A. S. (1912). Ibid. p. 275. 



Roubaud, E. (191 1). Compt. Rend. Acad. Sci. pp. 406 and 637. 



Simpson, J. J. (1912). Bull. Ent. Research, vol. iii. p. 301. 



Zupitza (tgog). Cf. S. 5. Bulletin, vol. 11. p. 1-49. 



