BIG GAME AND TSETSE FLIES 
121 
is well established, the tsetse fly is one of the few species of 
diptera, which does not lay eggs, but extrudes a live larva. 
It is, however, unnecessary to labour the point. 
The sub-committee have had evidence from Sir H. Johnston, 
Sir Alfred Sharpe, Mr. F. C. Selous, Mr. F. Vaughan-Kirby, 
Mr. R. C. F. Maughan, Dr. Park-Ross, Sir David Bruce, C.B., 
Mr. R. T. Corjmdon, Mr. Hudson, Mr. Dacre, and many others. 
Among the fallacies commonly current in respect of the 
tsetse fly many are connected with its life history. These 
particularly originate with untrained observers, and among 
them may be mentioned the belief that the tsetse fly lays eggs ; 
that its eggs are laid in the dung of buffaloes ; that the stock 
disease (nagana) is due to a trypanosome of which the hosts 
are certain animals, and those only. That fallacious theories 
upon these subjects have been current and adhered to with 
tenacity is not surprising, because it is only of recent years that 
any real attempt has been made to study the life history of 
Glossina and its relation to wild and domesticated animals. 
Moreover, certain facts have apparently supported these 
theories. It is only recently that scientific investigation has 
shown how unreal is the support they give. Opinions once 
held, it is difficult to shake them, even though the incorrectness 
of the premises upon which they are based is exposed. The 
conclusions to which your committee has come upon the 
evidence collected are as follows : 
1. For the existence of Glossina certain climatic conditions 
are essential. These are a precise degree of warmth and, in 
respect of certain species of the fly, humidity of atmosphere. 
Where these climatic conditions do not obtain Glossina is not 
present. Natural conditions which are favourable to the 
presence of the tsetse fly are usually malarious, and con- 
sequently undisturbed by hunters, except in the dry season. A 
result of this fact is that the game retreats to these natural 
sanctuaries from man, and its concurrence with the fly 
leads to the belief that the fly is dependent upon it for 
existence. 
2. The food supply of Glossina consists principally (though 
perhaps not entirely) of the blood of any warm-blooded animal. 
There is evidence to show that the fly also feeds upon the blood 
