. 99 



1908, " of the existence of G. morsitans in large numbers where 

 there was little or no sign of the larger mammals/' Major Stevenson 

 Hamilton feels " fairly convinced that/' within the area in question, 

 " the fly .... exists to a great extent independently of the 

 blood of large quadrupeds." 



In his paper on the " Blood-sucking Insects of Eastern Tropical 

 Africa " (103), Dr. S. A. Neave, who has closely studied the East African 

 Tsetse-flies, expresses himself as follows : " With regard to the rela- 

 tions of G. morsitans with game, I must unhesitatingly group myself 

 with those who consider that the presence or absence of big game is 

 not the primary factor in determining the distribution of the fly. That 

 the presence of a large quantity of big game within a morsitans area 

 might influence the numbers of the fly by increasing the food supply 

 is probably true, but that the game materially affects the distribution 

 of the insect I do not for one moment believe. The majority of those 

 who hold the opposite view have acquired their experience in Northern 

 Rhodesia and Nyasaland and .... have probably been misled 

 by peculiar and abnormal circumstances. It is now, I think, pretty 

 generally admitted that, north of the Zambezi, at any rate, there is 

 no special relation between G. morsitans and buffalo. Certainly in 

 this part of Africa their distribution by no means coincides. Where 

 it does so, these animals are certainly very attractive to the fly, 

 probably because they are slow-moving and are usually in herds of 

 some size." 



In concluding his remarks upon G. morsitans the author writes : 

 " In view of the strong probability that this species can feed on a great 

 variety of vertebrate life, the mere destruction of the large game would 

 seem at first sight absurd, unless the said game can be proved to be 

 the sole reservoir of a noxious trypanosome. If a serious attempt is 

 to be made to starve out the insect, the only logical step would involve 

 the removal or destruction of all such classes of animal life, including 

 man and his domestic animals." 



As regards the efficacy of game destruction in reducing the numbers of 

 G. morsitans, it was found in Southern Rhodesia, in 1916 (17), in the 

 area between the Sengwe and Umniati Rivers, that the fly appeared 

 to be extending its range ; and that, although the game laws had been 

 suspended, there was no appreciable decrease in the numbers of game, 

 except in the case of the elephant, to which to some extent hunters 

 were devoting their attention in preference to other game. It also 

 appeared that the opening of certain areas to free shooting had had the 

 effect of driving game thence into inhabited country. Nevertheless 

 the Director of Agriculture considered that, in a clearly defined zone, 

 the extermination of game with the aid of natives was feasible and 

 likely to have the desired result. 



Later in the same year Mr. R. W. Jack reported that G. morsitans 

 was continuing to spread rapidly in certain parts of the Sebungwe 

 district, Southern Rhodesia. In the south-west corner of the great 

 belt in that region, the fly had advanced in a southerly direction from 

 the Mzola to the Kana River, and in a westerly direction to the Shangani 

 River. At the head-waters of the Mzola River, although no actual 

 advance was recorded, G. morsitans was certainly increasing rapidly. 

 An advance of seven or eight miles had been made up the Sengwe 

 River since 1914, and the fly was reported also to have spread north- 

 ward near the Sengwe and Sasame Rivers ; at other points visited 

 by Mr. Jack no advance since 1914 was apparent. In some of the 



