32 NATURAL HISTORY OF GLOSSINA PALPALIS 



catch and the hunger of the flies was borne out by the 

 behaviour of flies on different islands visited by Fiske 

 and myself in 1914. (See Chapter VI.) Certain islands, 

 notably Kimmi and Yempata, were remarkable for the 

 avidity with which the flies bit ; on Kimmi they even 

 flew out to the canoe before it reached the shore. On 

 both these isles the percentage of females was higher 

 than usual ; on Kimmi it averaged 53 per cent., on 

 Yempata 37 per cent. 



The curiosity and spirit of investigation of the male 

 fly was shown by a little experiment on Tavu Island. 

 I noted that during the passage through some thick 

 Kinsambwe bushes many leaves became reversed so 

 as to show the silvery under surface. Male Tse-tse 

 often settled on them as if attracted by the novelty. 

 I therefore spent some time catching every fly that settled 

 on my white net, held out conspicuously, and in one hour 

 thus caught twenty-six males, but only six females. 

 I then caught from off my clothes those flies that had 

 settled and lowered the proboscis intending to feed ; 

 there were ten females to eight males. Male flies may 

 very often be seen which seem to have no desire to feed, 

 but merely to rest in a conspicuous position, often on a 

 rock hot with the sun ; possibly they are on the watch 

 for females. There can be no doubt that they use their 

 eyes in the search for food : it has long been known in 

 the case of G. morsitans that a man on horseback or cycle 

 moving will attract flies where none have been noticed 

 while he was stationary. Palpalis would often alight on 

 the canoe drawn up on the beach ; presumably the large 

 black object was thought at first to be a hippopotamus ! 



The fact that the fly will often sit on a rock hot with 

 the sun is of interest, seeing that they are apparently 

 dependent upon shade, and are susceptible to variations 

 in the humidity of the atmosphere. I am convinced, 

 however, that so long as palpalis has a shady base it will 



