91 



however, that the tsetse is willing to feed on the smaller animals. On 

 the more active ones it would have little chance of obtaining a meal 

 when they are alert. Many of the smaller mammals are nocturnal, and 

 spend their days sleeping in hiding-places which are the same in many 

 cases as those which the tsetse haunts. This applies also to many of the 

 nocturnal birds. It is a very common experience to see tsetses fly out 

 of a burrow in the ground or a hollow in a tree, while the numbers of 

 pupae which are taken in such positions show that they are much 

 frequented by the female flies. When asleep, such animals would 

 probably form a ready prey to the fly, as is the case with man and 

 the mosquito .... It is therefore possible that these small 

 animals supply a larger proportion of the food of the tsetse-fly than 

 is generally supposed." 



In Nyasaland, Lamborn (84) considers that G. morsitans derives 

 part of its food from baboons, which occur in all districts in which 

 this species has been studied. Bare-necked birds, such as vultures, 

 according to this author, may furnish food material to a slight extent, 1 

 but in trie case of other forms Lamborn believes that the presence of 

 feathers renders feeding very difficult. The scarcity of reptiles appears 

 to negative the supposition that these animals may furnish a blood 

 supply, and small lizards are probably too active to be of material 

 value as a source of food. Tests with toads and tree-frogs made by 

 Lamborn yielded negative results. It should, however, be noted that 

 the evidence that G. morsitans does not normally feed on non- 

 mammalian blood is less conclusive than would appear from Lamborn's 

 statements. The preference of G. palpalis, at any rate, for the blood 

 of reptiles, such as crocodiles and monitors, under natural conditions 

 is well known, 2 and even in the laboratory a similar catholicity of 

 taste is displayed by this Tsetse fly. " Minchin, Gray and Tulloch 

 (1906)," writes Roubaud (96), " fed Glossina palpalis in captivity on 

 lizards, chameleons and birds ; Zupitza (1908) induced this fly to bite 

 fish of the genus Periophthalmus ; and in the laboratory at Brazzaville 

 we ourselves have fed it with ease on toads (Bufo regularis Reuss), 

 frogs, young crocodiles, chameleons, fishes of the Silurus group living 

 in streams which are non-perennial, small nocturnal lemurs (Galago 

 demidoffi Fisch.), etc. G. palpalis also bites birds, although not so 

 readily." 



1 At Kashitu, Northern Rhodesia, Lloyd (91) saw two G. morsitans on the bare 

 skin of the neck of a ground hornbill, one being in the act of sucking blood. 



- Fiske (54) states that on Lake Victoria, in Uganda, the crocodile and the 

 monitor (Varanus}, both of which are amphibious in habit, are the two favourite 

 hosts of G. palpalis. Not only are they the most attractive to the fly, but the 

 most favoured breeding grounds of the insect are frequently identical with spots 

 selected by the crocodile for breeding places, or by Varanus as a basking ground. 

 G. palpalis therefore becomes almost a specific parasite of these reptiles. It is 

 considered by Fiske that complete extermination of the four principal hosts 

 (crocodile, Varanus, situtunga and hippopotamus) on Lake Victoria would 

 cause a reduction in density of infestation amounting to 95 to 99 per cent. 

 Many years ago the late Robert Koch stoutly proclaimed the paramount import- 

 ance of the crocodile as the principal host of G. palpalis in what was then German 

 East Africa. With reference to G. palpalis Fiske writes : 



"There are two tests for distinguishing between attractive and repulsive 

 hosts : 



"(1) An attractive host is apt to collect a 'following swarm of fly.' 

 This curious phenomenon is associated with the assembling of the 

 sexes. . . . 



" (2) The range of fly especially its range inland from the shore is 

 likely to be notably extended through the presence of favoured 

 hosts." 



