TO THE LUANGWA VALLEY, NORTH-EASTERN RHODESIA. 305 



Xotes on the chief Bking Insects and Ticks met with in 

 the Lnangica Vcdleij. 



Glossina pcdpalis appears to be absent from the whole valley. It is 

 decidedly doubtful whether this species could survive in this locality, even if 

 introduced there. We know, from the w^ork of Roubaud and others, that a very 

 considerable degree of atmospheric humidity is necessary for the w^ell-being 

 of this species. Now^ the Luangwa Valley is notorious, locally at least, for 

 being intensely dry, as w^ell as being extremely hot. This condition of 

 things obtains during the greater part of the six months of the dry s;«nson 



M 



Fip. -2. — A sniid-hiiiik in the bed of the ]Mid Luangwa Eiver, 



and even at intervals in the wet season, the rainfall being relatively small. 

 Apart therefore from considerations of geographical distribution and the 

 influence of the high ground of the Congo- Zambesi w^atershed, wdiich I have 

 pointed out elsewhere *, it would seem that the climatic conditions are 

 unsuitable for (r. pcdpalis. 



For an account of the dry character of the Luangwa Valley, and of the 

 causes thereof, reference may be made to a paper by Mr. L. A. Wallace in 

 the Journal of the Royal Geographical Society, April 1907, p. 382 seq. 



Even supposing the adult fly could survive the long and intensely hot dry 



* Journal of Economic Biology, 19U9, \ol. iv. pt. 4, pp. 109-114, 



