126 B. MOISER—DESCRIPTION OF HAUNTS OF GLOSSINA TACHINOIDES, &C. 
On investigating the “ bush” some 400 or 500 yards on either side of the 
river, no flies were seen at all, and at one or two small villages, situated a mile or 
so from the river, I was informed that the flies never appear there. So that 
apparently the “belt ” is confined to the immediate course of the river Hawal, 
and as far as I was able to ascertain, extends for at least ten miles along the 
river, the tsetses living at particular spots only, the intervening spaces being 
normally free from them, except when the flies follow human beings who traverse 
these areas. 
These two isolated and comparatively restricted fly-belts would seem to afford 
very favourable conditions for studying the factors which determine the distribu- 
tion of these particular species of Glossina; but the investigation would 
necessitate a residence of at least some months in the vicinity. 
The fact that the flies are so curiously localised even within the limits of the 
fly-belt may prove of some importance ; anil it might be possible to ascertain 
what it is that influences them to congregate, as they do, about certain particular 
bushes. 
