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



surrounding them. I have more than once seen this species swarming in long 

 grass on plains of some size, from a half to a mile or more from the line of bush 

 at the edge. In such a locality there would probably be a few isolated trees or 

 bush-covered termite mounds, and in some cases these would probably be the 

 sites for the deposition of pupae. When such a locality is burnt clear, especially 

 if there is a high wind and the grass burns fiercely, large numbers of flies are 

 undoubtedly destroyed. The survivors will generally be found on the outskirts 

 of the surrounding timber. Whether this species could exist on plains of great 

 size covered only with long grass is impossible to say, since, so far as I am aware, 

 this type of country does not occur in Tropical Africa. It must be remembered 

 that the presence of long and rank species of grass denote a soil of at least 

 moderate fertility, and long grass would therefore be almost certainly accompanied 

 by more or less timber. In large short-grass plains, such as those to the east of 

 Lake Bangweolo, this fly does not occur, nor from the paucity of the cover would 

 it be expected to do so. G. morsitans also appears to avoid the other extreme, 

 viz : — dense forests where the atmosphere is cool and damp. 



My experience of this species in the northern part of its distribution, in the 

 upper Nile Valley, has been very limited, but I obtained a few specimens near 

 Masindi Port on the Victoria Nile in December 1911 and also in the valley of 

 the Kafu River near by. It is perhaps of some significance that this is a 

 decidedly drier area than all the southern part of the Uganda Protectorate and 

 it is also about that point that one begins to enter a rather thin bush and wood- 

 land country, presenting a great general resemblance to that of Northern 

 Rhodesia and Nyasaland. 



G. morsitans would appear to have a rather less marked seasonal variation in 

 numbers than some other species of Glossina, being usually fairly numerous 

 throughout the year where it does occur. Some observers have considered that 

 the range of this species is much more restricted in the dry season than in the 

 wet. I have not personally noticed this to be very marked in Nyasaland or 

 Northern Rhodesia, except that, as explained above, the fly is driven out of more 

 open areas into shadier bush by the grass fires. 



Reference has been made in a recent paper by Dr. Sanderson to the 

 " migratory " habits of this species. The actual evidence on this point however 

 seems to be almost nil, but it is certainly an important question about which we 

 shall know little of value until some definite flight experiments with marked 

 individuals are carried out. There is no doubt that the distance to which this 

 species will follow its victims is much greater than that of G. paljwlis. 

 Considerable allowance in studying the range of this species must be made for 

 the state of the weather, to which it is very sensitive. It must be remembered 

 that in dull rainy weather, it would be quite easy to go through a patch of 

 country where this fly was numerous and see scarcely a single individual. In 

 this way a quite erroneous impression of its abundance or otherwise might be 

 gained. G. morsitans delights in hot sunny weather and is particularly noticeable 

 under such conditions. In the rainy season it seldom bites unless the sun is 

 shining, but given suitable conditions, such as occur for instance in the Luangwa 

 Valley during the last three months of the dry season, this species will be ready 

 to bite from an hour after sunrise until midnight or even later, especially if 



