THE WILD FAUNA OF THE EMPIEE 17 



has led to the concentration of an enormous amount of attention 

 upon a group of insects about whose habits and mode of hfe com- 

 paratively little was previously known, the demonstration that 

 the organism which is the cause of sleeping sickness is spread by a 

 particular species of tsetse-fly has resulted in the accumulation 

 within the last five years, by investigators in various parts of 

 Africa, of a number of fresh facts bearing upon the bionomics of 

 the genus Glossina. At the present time, therefore, we are able to 

 form a far truer conception of the relation between the various 

 species of tsetse and big game than was possible in 1903. Let us 

 take the most important species, Glossina palpalis, first. That 

 this tsetse-fly is dependent upon big game for its subsistence is dis- 

 proved by the experience of Professor Minchin and Messrs. Gray 

 and Tulloch, E.A.M.C.,^ in Kimmi, a small uninhabited island of 

 the Sesse group, in Lake Victoria, Uganda. It is true that we are 

 told that the island is ' a regular feeding ground for hippopo- 

 tami, '^ but the ordinary game animals are entirely absent. 

 Crocodiles, however, are 'very numerous,' and 'cormorants, 

 other diving birds, and weaver birds are very plentiful.' * The 

 whole island swarms with tsetse-fly (G. palpalis).' This species 

 of tsetse is particularly closely associated with water, which is not 

 invariably the case with regard to certain others, such as Glossina 

 morsitans and G. fusca. As a rule G. palpalis is not met with 

 more than 50 to 100 yards from the water's edge; according to 

 Dr. A. D. P. Hodges, in Unyoro and the portion of the Nile Valley 

 lying within the Uganda Protectorate, ' the outside limit may be 

 given as 300 yards.' ^ On Lake Victoria Messrs. Minchin, Gray, 

 and Tulloch state that the fly haunts the lake-shore in a remark- 

 able way, and that, since there is nothing in its breeding-habits to 

 account for this, the food-supply is the probable attraction. These 

 members of the Sleeping Sickness Commission write that the 

 ' vast numbers of cormorants and other fish-eating birds ' found 

 ' along the shores of the lake and on all the small islands might 

 furnish one constant and important source of food.' In the 

 laboratory it was observed that the fly * fed very rapidly on captive 



* ' Reports of the Sleeping: Sickness Commission of the Royal Society,' 

 No. VIII. (February 1907), p. 128. 



2 As to Glossina palpalisi and hippopotami, a recent observation by Dr. 

 A. D. P. Hodg:es, Medical OflBcer, Uo^anda Protectorate, is of interest. Accord- 

 ing to Dr. Hodges, the Bachopi people (in Western Uganda, in the vicinity of 

 Fajao)'say that Glossina palpalis "follows the hippopotami," but it was 

 found in many places where these animals seldom or never come, and was 

 absent from others where they abound ' {Ihid. p. 91). 



8 Ibid. p. 90. Of course there are exceptions to this rule : Dr. J. L. 

 Todd, writing of G. palpalis in the Congo Free State, remarks that the fly 

 has extensive powers of flight, and is occasionally found as much as half a 

 mile from water. Nevertheless it appears to be 'very local in its habits. As 

 has often been observed, not a single fly may be seen at 100 yards from a 

 river, although its banks swarm with them ' (Annals of Tropical Medicine and 

 Parasitology, vol. i. No. 1 (February 1, 1907). p. 63). 



B 



