498 



OTHER BLOOD-SUCKING FLIES 



Glossina palpalis (Fig. 236) is a large dark species with black- 

 ish brown abdomen and with gray thorax having indistinct brown 

 markings. This species is found over the whole of West Africa, 

 from the Senegal River to Angola, and east to the upper valley of 

 the Nile and the eastern shores of the central lakes (Fig. 231, \\\). 

 Its range is thus nearly coincident with that of Gambian sleeping 

 sickness. This species, more than any other except possibly 

 G. tacMnoides, which occurs around the southern border of the 

 Sahara Desert, is dependent on the presence of water. Its natu- 

 ral range is said seldom to exceed 30 yards from the edge of water, 

 and the distance that it will follow animals or man is not more 



Fig. 236. Glossina palpalis, carrier of Gambian and Nigerian sleeping sick- 

 ness. X 4. (After Austen.) 



than a few hundred yards. Muddy, reedy sloughs or swamps 

 are not frequented by this fly, but rather sandy- or gravelly- 

 banked streams with abundant overhanging vegetation. In 

 the rainy season the flies extend their range to headwaters which 

 are dry during the remainder of the year and retreat again with 

 the drying up of the water. It is feared that this species may 

 sometime bridge the short gape between the headwaters of the 

 Congo and the Zambesi, and become established along the latter 

 river and its tributaries, carrying sleeping sickness with it. 



' This fly probably feeds naturally on a number of different 

 animals. Wild game, especially the Situtunga antelope, is 



