278 GLOSSINA MORSITANS [CH. 



Ubangi, Northern and Southern Nigeria, Dahomey, Togoiand, 

 Gold Coast Colony, Ashanti, Northern Territories, Ivory Coast, 

 French Guinea, Gambia and Senegal. 



Bionomics. In the present place it is only possible to give 

 a brief account of the more important observations on this 

 subject. The reader desirous of further information will find 

 an excellent summary of all the earlier observations on G. 

 morsitans in Austen's Monograph of the Tsetse-flies. 



As a general rule, G. morsitans is confined to certain re- 

 stricted and often very well-defined tracts of country, known 

 as " fly-belts," the boundaries of which, however, are liable 

 to variation ; for Hall found that in North Eastern Rhodesia 

 the fly considerably extended its range of distribution between 

 the years 1904 and 1909, and Neave is of the opinion that the 

 flies are now recovering the ground lost at the time of the 

 rinderpest, when G. morsitans disappeared from the Transvaal. 



Usually the fly prefers a region in which there is sufficient 

 vegetation to provide a moderate but not excessive cover, and 

 a hot. and moderately dry climate. It seems to be almost 

 independent of surface water and is most active in a dry 

 atmosphere ; though in some districts the flies seem to be 

 more common in the neighbourhood of rivers. 



In Nyasaland they are never found in open grass country, 

 but only in bush, especially in those portions of the forest where 

 Sanya trees and antelope are most abundant. Dense forest 

 is generally avoided by the flies, but they prefer regions 

 scattered with trees that give shade. Sir Alfred Sharpe's 

 observations in this region are of considerable interest, especially 

 on the effect of cultivation on the prevalence of the fly. He 

 states " I am acquainted with villages which are situated inside 

 fly-areas and wherever the natives build their villages in such 

 localities, and clear ground for their food-gardens, tsetse immedi- 

 ately disappear from the cleared ground. I have often noticed 

 that, when approaching those villages from the bush, fly which 

 are following the carriers, or are actually upon their persons 

 biting them, will gradually disappear after entering the cleared 

 ground, and by the time the village is reached, no fly can be 

 seen. On the other hand, I have known cases where villages have 



