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HANDBOOK OF THE TSETSE-FLTES. 



(Genus GLOSSINA.) 



CHAPTER I. 



THE GENERAL CHARACTERISTICS AND DISTRI- 

 BUTION OF TSETSE-FLIES (GENUS GLOSSINA). 



The insects forming the subject of this volume 

 General Characteps ^ , -t , ,. i i ■ i i 



of Tsetse-flies : how ™^y "^ described as ordinary-looking dark 



to distinguish them brown, blackish, yellowish-brown, or yellowish 

 from other flies. ^.^^^ varying in length from about 6 or 8 

 millimetres, as in the case of Glossina tachinoicles, to as much as 

 13 or 13-5 millimetres in that of G. brevipalpis or longipennis* 

 with a prominent proboscis in all species. The hinder half of the 

 body, or abdomen, in the species belonging to the Glossina 

 morsitans group and in G. tachinoides is of a paler colour and marked 

 with sharply defined dark brown bands, which are interrupted 

 on the middle line ; the abdomen, however, is invisible when the 

 insect is at rest, as it is then concealed by the wings. The sexes 

 of Tsetse-flies can readily be distinguished when specimens can 

 be examined, since in the male the external genitalia form a 

 conspicuous knob-like protuberance (hypopygium) beneath the 

 end of the abdomen (see Figs. 14 and 15, pp. 50, 51), which is 

 absent in the female. 



* These measurements aro only from the head to the end of the body 

 and are exclusive of the proboscis and palpi, which project horizontally in 

 front of the head. In the crossed lines on the coloured plates, however, 

 the vertical line indicates the average length of the whole insect, including 

 the proboscis, the transverse line showing the wing-expanse. 



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