86 GL. MOESITANS.— EATIO OF SEXES. 



Habits, etc. (See Chapter I.). 



It has already been pointed out at the commencement of 

 Chapter I. that the name Glossina morsitans is usually quoted aa 

 if it were that of the only known species of the genus. Although 

 this, of course, is a mistake, nevertheless, if it is permissible 

 to draw any conclusion from the material at present available 

 for examination, Gl. morsitans is one of the two commonest 

 Tsetse-flies of South and Central Africa. But since its range in 

 this region is practically co-extensive with that of Gl. pallidijpesy 

 all statements in accounts of South African travel and sport as 

 to the occurrence and habits of " the Tsetse-fly " or " the South 

 African Tsetse-fly " must for the present be regarded as referring 

 to both species indiscriminately : while owing to the fact that 

 both Glossina longtpalpis and Gl. palpalis would appear also to 

 occur on the Zambesi, some of the phenomena hitherto attributed 

 to Gl. morsitans should perhaps really be ascribed to one or both 

 of the latter species. With this explanation, readers who desire 

 to learn the habits of Glossina morsitans may be referred to 

 Chapter I., where all that is known on this subject will be found 

 fully discussed. 



It will have been noticed that, in the foregoing list of speci- 

 mens examined, out of seventy-one examples only twenty-one are 

 females. The whole of the fifteen specimens, too, brought back 

 by Mr. Christopher HeseltLne from the Tzende River were males, 

 as were also the six specimens of Glossina palpalis taken by the 

 author in Sierra Leone ; while out of fifty specimens of Gl. 

 pallidipes from Machakos, only three are females. This would 

 suggest the idea that in some at least of the species of Glossina 

 the two sexes may have slightly different habits (although they 

 both suck blood *), in consequence of which the female is more 

 easily able to escape observation or avoid capture : it should be 

 noted, however, that in the twenty specimens of Gl. morsitans 

 collected by Dr. Schilling, in Togo, the sexes are equally divided. 

 In view of the above facts there can be little doubt that Sir 

 John Kii'k's statement [28] that only on one occasion did he 

 " obtain two of what may be the male insect," was due to his 

 having confused the sexes, unless indeed he happened to have 

 collected at a season when the usual ratio of the sexes was reversed. 



• Among the Tabanidaa (Horse-flies), in which the females alone suck 

 blood, while the males frequent flowers, the females are much the more 

 common. 



