94 BIONOMICS OF GLOSSINA BREVIPALPIS. 



temperature is abnormally low.* Although continuing to bite 

 and flv about "for some time after dark" (Sanderson), G. brcri- 

 palpis appears not to bite during the actual night hours, and 

 specimens kept in captivity in glass cylinders were found in 

 complete darkness to be perfectly still (Stuhlmann). Like G. pcd- 

 palis and blood-sucking flies in general, the present species 

 displays a predilection for dark-coloured animals and surfaces. 

 Stuhlmann states that he has frequently noticec^ that, when a 

 light- and a dark-coloured mule were moving side by side, only 

 the latter was attacked, and Sanderson writes : — " The flies bite 

 through dark clothes, but have never been seen to settle on white 

 surfaces."' 



As to the relation of G. hrevipaljyis to game, Davey observes 

 that wherever he met with this fly in Nyasaland " game 

 (antelope, warthog, etc.) was abundant." Once during the wet 

 season, having shot two bush-pigs about sunset, on going up to 

 the animals he found several G. hrevipalpis settling upon the 

 carcases and " apparently trying to suck blood " from them, 

 although for some time previously he had searched for the flies 

 without success. 



It will have been noticed that, out of the 359 specimens of 

 this species examined by the present writer, only 42 were 

 females, and the enormous preponderance of males over females 

 usually seen among captured specimens has been noted both by 

 Stuhlmann and Davey. f It is pointed out, however, by the 

 former author that, as in the case of other flies, it is shown by 

 breeding G. hrevipaJpis in captivity that the two sexes are 

 produced in approximately equal numbers. In order to catch 

 females, Stuhlmann states that it is necessary to use animals 

 such as cattle and mules as decoys, but even so he observes that 

 they are much more diflficult to capture than males. He thinks 

 it probable that " the gravid females are much more wary and 

 move about less than the males, and are consequently more rarely 

 caught." 



* In order to keep captive flies alive, a meal of blood at intervals of 

 froin four to sis days is necessary ; by feeding every fourth or fifth day, 

 Stuhlmann has kept G. brevipalpis at Amani for considerable periods — in 

 the case of individual females, for upwards of four months. 



t In German East Africa, fly-boys sent out by Stuhlmann into the 

 Mkulumusi Valley below Amani, brought back in one week over 1,200 

 G. brevipalpis, of which only 90 were females. At Kaporo, near the north 

 end of Lake Nyasa, out of 117 G. brevipalpis caught in the evenings in 

 August (dry season), all were males (Davey). On the other hand : " Seven 

 were captured at the same place and time of year about midday, and of 

 these, four were males and three were females." 



