54 NATURAL HISTORY OF GLOSSINA PALPALIS 



able with glasses to see Cacergates in attendance on a 

 hippo that was grazing on Bugalla fly ground, evidently 

 on the look out for flies full of hippo blood ! 



Predaceous two-winged flies of the family Asilidae 

 have once or twice been seen to be devouring Olossinae, 

 but I do not think that the Asilid is of any importance 

 as a regular enemy. 



On the whole, it seems that the chief enemies of Olossina 

 are among the Hymenoptera, but I am inclined to think 

 that great loss of life does not result. Olossina has 

 such an extraordinarily slow rate of reproduction that 

 it can have few enemies : the greater the number of 

 offspring the more must be destroyed by enemies if the 

 species is to be kept within bounds, and vice versa. Clim- 

 atic conditions, in my opinion, together with facilities 

 for breeding, are the most important influences affecting 

 the numbers of the fly. 



We now come to the question of the " breeding grounds " 

 of palpalis, on which a great deal of work has been done. 



The very peculiar method of reproduction of the genus 

 Olossina was reported by Bruce in his papers on Nagana ; 

 hitherto Olossina morsitayis had been supposed to deposit 

 its eggs in buffalo droppings, and this was held to account 

 for the supposed fact that this Tse-tse could not live 

 apart from the buffalo. 



When palpalis was proved to be the carrier of Sleeping 

 Sickness efforts were made to discover its pupae, with a 

 view to the possibility of destroying it in large numbers 

 when it could be easily reached. 



Dr. A. G. Bagshawe ^ in Uganda was the first to find 

 the pupae of palpalis : they were deposited around the 

 bases of stems of banana plants. Later he found them 

 sparsely under sundry bushes and masses of creepers, 

 but never in such great numbers as can now be found. 



Dr. C. Marshall and Lieutenant A. D. Eraser, R.A.M.C, 



1 Reports of the Sleeping Sickness Commission, 1908, IX, p. 48. 



