8 



that in the former area the absence of big game is only temporary, 

 while the continued presence of wart-hog and duiker, afiord a con- 

 stant supply of food for the fly, and shade conditions are excellent 

 in that neighbourhood ; shade conditions, however, along the Hanyani 

 are bad, the banks being too thickly wooded for G. morsitans and the 

 neighbourhood too open to afford shade. It is claimed that there is 

 a vital association of G. morsitans with big game on the ground that 

 it retired before the advance of civilisation in the Transvaal, where, 

 for many years, the wholesale destruction and driving away of the 

 larger fauna was the sole modification of natural conditions due to 

 the advent of the European, and no extensive clearing of the forest 

 occurred until after the fly had disappeared. Tsetse is stated to 

 have disappeared from large tracts of country immediately after 

 the outbreak of rinderpest in 1896, and has never reappeared in 

 certain localities on the Limpopo and Sabi Eivers, in Bulalima- 

 Mangwe and Bubi districts, near Selukwe in the Gwelo district, 

 along the Zambesi near the Victoria Falls or in the Wankies 

 district ; but in an editorial note it is stated that in many of these 

 areas the fly had already gone before the destruction of the 

 game by rinderpest. In other areas a nucleus was left, but 

 large tracts of country were free which are now infested, notably 

 that between the Hanyani and Angwa Rivers. A nucleus probably 

 remained in the Lomagundi district and has extended greatly in recent 

 years ; in the Urungwe sub-district odd specimens were encountered 

 at a number of isolated spots between 1905 and 1910, and the fly 

 seems to have survived the rinderpest in very small numbers in 

 scattered localities, and, though failing to increase to any extent, 

 persisted until recent years. Tsetse has increased and spread since 

 the rinderpest only in those parts of S. Rhodesia where big game 

 has increased, notably in the Sebungwe area, west of the Sengwa 

 River, where there have been no Europeans living. A map shows the 

 limits of the fly in Sebungwe in 1896, 1904, 1907, 1910 and 1914 

 respectively. Tsetse has greatly decreased of late years in the Hartley 

 district in those parts where the big game has been most effectively 

 destroyed or driven away. An area including the Hartley fly belts 

 was shot over to a great extent from 1905-1908 and from 1909 onwards, 

 with the result that the district is almost destitute of the larger fauna, 

 while all evidence from Europeans and natives agrees that the fly 

 was more numerous before 1909 than afterwards. The main obstacle 

 to the acceptance of the theory of big game being necessary to the 

 tsetse is the fact that many possible sources of blood other than that 

 of ungulates exist in the African forests, but the vast bulk of these 

 cannot, in the opinion of the author, serve as permanent sources of 

 food supply. It is stated that G. morsitans is rarely found in the 

 haunts of reptiles or amphibia, while Insectivora, Cheiroptera and 

 Edentata may be excluded on account of their nocturnal habits. 

 Avian blood is a possible source of food, but the auther considers 

 that birds are but rarely attacked by this tsetse. The smaller 

 antelopes and Quadrumana provide an irregular food supply, but 

 it is contended that the food essential to the continuance of the fly 

 is only provided by the larger Ungulata. Evidence in S. Rhodesia 

 is against the existence of a special association between tsetse fly and 

 buffalo, the distribution of the two not being generally coincident. 



