﻿280 S. A. NEAVE — NOTES ON THE BLOOD-SUCKING 



can be no doubt that in very hot and dry weather, such as at the time mentioned, 

 both sexes absorb considerable quantities of water. During this period the 

 females very rarely attacked animals or man, the natives alone appearing to be 

 bitten, and then only occasionally, when actually at the water-holes where the 

 flies were swarming. 



As I have already pointed out,* some of the more fragile and slender species 

 of Tabanas appear to be able to drink by alighting on the surface of the water 

 and passing the proboscis through the surface film. Though I have never 

 actually seen it happen, I am inclined to think from their behaviour that some 

 species of Haematopota and Chrysops do the same, since I have once or twice 

 seen the males skimming to and fro over the surface of the water, apparently 

 wishing to alight upon it. 



In British East Africa the conditions in respect of Tabanidae are somewhat 

 different and more complicated, since there are two fairly well marked rainy 

 seasons. The most important of these is that from the end of March to about 

 the end of May, there being another short rainy period about November. In 

 this region therefore most species will probably be found to have at least two 

 broods during the year. The hottest and driest months are from the beginning 

 of January to the middle of March, and at this period few if any Tabanidae 

 are to be found, at least in the lower-lying parts of the country. When however 

 I was in the hot dry country near Voi, in March 1911, I found some evidence 

 that several species emerge from the pupa a week or two before the rains break 

 in the low ground, as in Nyasaland and Rhodesia. On the other hand, in the 

 much cooler and less dry highlands, especially in the more forested parts, as on 

 the slopes of Mt. Kenya and on the Aberdare range, many species of Haematopota 

 were on the wing during the driest season and therefore probably all the year. 



In Uganda the conditions are again somewhat different. There, though there 

 are nominally two wet and two dry seasons, they are very ill-defined, except in 

 the Nile valley and parts of Ankole. The natural consequence of this is that, 

 owing to the more or less humid conditions all the year, many species of 

 Tabanidae, especially the forest-loving ones, seem to be on the wing throughout 

 the cycle of the seasons. 



Thus it will be seen that the best time for collecting Tabanidae in Eastern 

 Tropical Africa, especially the males, is immediately before and after the 

 beginning of the rains. Since the males appear seldom to stray very far from 

 their breeding-places, they should, particularly in the case of Tabanus and many 

 species of Haematopota, be searched for in the immediate vicinity of water, on 

 the damp mud or sand in river beds or on the vegetation bordering it. The drier the 

 country is, and particularly if the river is reduced to isolated pools, the better the 

 chance of success, since the drinking places are thus much more easily located. 

 In a running stream in such a season I have taken some numbers of both sexes 

 basking in the sun on branches of trees and shrubs overhanging the water. A 

 rock or log of wood just above the surface of the water is also a very attractive 

 spot, and I have often seen my collectors attracting many Tabanidae and other 

 Diptera by scattering water on such surfaces. 



* Bull. Ent. Res. I, p. 311. 



