176 SOME ETHIOPIAN REPTILES, FISHES, AND INVERTEBRATES 



sitting motionless on the bare skin of a native. When eager to bite, it is with 

 great difficulty that they can be driven away. All are agreed that tsetses prefer a 

 black skin to a white one, and dark clothes to light-coloured garments ; conse- 

 quently, if a European be accompanied by natives, he is but seldom molested by 

 these pests. When a tsetse is about to feed, it spreads its legs, and more especially 

 the first pair, so as to bring its whole body nearer to the skin of its victim ; and in a 

 second or two the whole proboscis is plunged in to its base, after which it is usually 

 withdrawn to a short distance before the body of the fly begins to become visibly 

 distended with blood. After gorging, the fly seeks shelter and repose in bushes 

 or grass. A sharp prick is usually felt as the proboscis is inserted ; but the natives 

 take little notice of the stabs of tsetses, disregarding them more than those 

 of mosquitoes. Although it can pierce khaki or a flannel-shirt, G. palpalis 

 does not as a rule attack through clothes. The bite or stab of tsetses is fatal to 

 most domesticated animals owing to the introduction of the germs of an elongated 

 parasite which undergo development in the red corpuscles of the blood. In the case 

 of the above-mentioned G. palpalis the parasite of sleeping sickness is introduced 

 in a similar way into the human body. Roughly speaking, the chief tsetse-infested 

 areas are situated in that portion of Africa lying between the southern tropic and 

 the 12th degree of N. latitude, although a belt on the east coast descends con- 

 siderably to the south of the former zone. Except on the upper part of the west 

 coast, most of the belts follow the river- valleys for longer or shorter distances into 

 the interior. The range of G. palpalis is very remarkable, extending as it does 

 from Cape Verde in the north-west, along the west coast to the mouth of the 

 Congo, and then up the valley and across the watershed into eastern Equatoria, in 

 the neighbourhood of the northern end of Lake Rudolf and the eastern side of the 

 Victoria Nyanza. The South African tsetse, or Livingstone's tsetse, as it might well 

 be called, has been detected infesting a small patch of country on the Bahr-el-Ghazal. 



In Uganda, where these flies abound, there are at least four species of tsetses, 

 of which G. brevipalpis is one of the largest. It is of a dark brown colour, and is 

 only on the wing in the morning and late evening, and seldom seen during the heat 

 of the day except in dull weather. It frequents the banks of rivers, especially 

 where there is a certain amount of cover. G. longipennis is only a little smaller 

 than brevipalpis, but much paler. It bites freely during the heat of the day and 

 seems to be entirely independent of water, chiefly frequenting barren desert 

 localities. Neither of these is definitely known to carry disease to man or 

 animals in nature. G. pallidipes is a smaller, brownish fly, frequenting river- 

 valleys, though probably less dependent on water than brevipalpis. It bites at 

 all hours of the day, and is believed to carry disease to domesticated animals. G. 

 palpalis, the chief one communicating sleeping sickness, is the smallest of all the 

 above-described species, and is very much blacker. In British East Africa it only 

 occurs, so far as known, in the Nyanza Province, and is confined to the belts of 

 timber on lake-shores and river-banks. 



The following account of the habits of these flies is taken, with some ab- 

 breviations and verbal alterations, from a report of the Committee of the Natal 

 and Zululand Game Protection Association published in 1911, the species referred 

 to being G. morsitans and G. pallidipes. 



