166 ENTOMOLOGY FOR MEDICAL OFFICERS 



As regards other features of the genus Glossina, the eyes 

 are large, and in both sexes are well separated ; the 

 mesonotum is generally marked in the manner illustrated in 

 Fig. 68, though some of the markings are in some species 

 indistinct ; and the abdomen is composed of 7 visible segments, 

 not including those that form the hypopygium. 



In repose tsetse-flies are distinguished from other blood- 

 sucking Muscidce by the fold of the wings and by the poise 

 of the proboscis. The wings are closed horizontally so that 

 one lies above the other, and the proboscis projects 

 horizontally. 



According to Stuhlmann one species of Glossina may 

 occasionally produce larvae parthenogenetically. 



Other blood-sucking Muscidce (like the Culicidcz) appear, 



Fig. (_ ^. 'ill ( 1 !ae of Mesonotum of Glossina. 



though preferring blood, to be able to subsist on other juices, 

 but blood is said to be a necessity of life for tsetse-flies. 



As regards their geographical distribution the flies of 

 this genus are restricted to the Ethiopian Region (p. 7), and 

 in that region there is only one species that is known to 

 exist outside continental Africa, namely, G. tachmoides, which 

 has been found in the south-west corner of Arabia. The 

 range of the genus in Africa extends from about 18° N. to 

 about 31° S. Within these limits Glossina is usually con- 

 fined to warm and damp situations, not very far distant from 

 water, where shade of some kind — of forest, or of scrub, or at 

 least of reeds — is obtainable, such natural stations being 

 usually known as " fly-belts." Tsetse-flies are said to be 

 absent from open shadeless plains. 



The connection of tsetse-flies with certain trypanosome 

 scourges of man and domestic animals, the elucidation of 

 which has made the names of David Bruce and Kleine as 



