206 . DR. JAMES J. SIMPSON. 



Again, between 22nd February and 23rd March 1916, another test was made with 

 the following result : — 3,842 tsetse were caught, or 128 per day. From 21st November 

 to 23rd December, 4,392 tsetse were caught, or 133 per day. 



It must be remembered that collectors were working in this area at several inter- 

 vening times, so that one is fairly justified in concluding that systematic trapping is 

 out of all question in such an area. 



This, it must also be remembered, was accomplished by trained, well paid, fully 

 equipped collectors, and I am of opinion that if the whole population in the area sug- 

 gested were put on to this work, there would be no appreciable diminution in the 

 number of tsetse. The expense, too, would preclude such an undertaking being 

 attempted. 



Systematic trapping with bird-lime I found to be less satisfactory than by means 

 of nets. Four colours of paper were used — light brown, red, black waterproof, and 

 green. These were most satisfactory in the order given. 



The following are the average numbers captured daily, five men being used for 

 each colour : — Light brown, 103 ; red, 89 ; black waterproof, 79 ; green, 45. 



In my Gambia report* I have already shown the marked preference of tsetse for 

 black over white in clothing. 



I then tried liberating tsetse in an enclosed room and smearing the bodies of 

 collectors with the following oils and essences : — oil of bergamot, oil of cloves, beech- 

 wood oil, oil of lavender, cedar wood oil, beech wood creosote, essence of oranges, and 

 essence of lemon. The tsetse were allowed to alight on and bite the collectors, and 

 only in two cases did these substances seem to act as a deterrent, viz., beechwood 

 creosote and beechwood oil. In the case of oil of cloves and the two essences there 

 seemed to be a marked attraction. The large quantities of these preparations required 

 precluded the experiments from being carried out on a large scale. 



Beechwood oil smeared over the hands and face acts as a deterrent to mosquitos 

 so long as the fumes persist. 



VII. Natural Enemies of Tsetse. 



The conservation or increase in the numbers of the natural enemies of tsetse is a 

 subject which might well repay consideration. Guinea-fowl and bush-fowl have been 

 mentioned by some writers, especially the late Professor E. A. Minchin. He recom- 

 mended that these species should be conserved and their range extended, as owing 

 to their scraping habits it was more than probable that they would feed on and destroy 

 tsetse pupae. To test the validity of this hypothesis I examined the stomach contents 

 of 379 of these birds. I found that by far the greatest proportion of the food of both 

 species consisted of guinea-corn and other seeds. From the animal kingdom the 

 following were found, beetles, Syrphid flies, Mantids, ants, bugs, grubs of various 

 sorts, millipedes, grasshoppers, Hymenoptera, molluscs, etc., but in no case did I see 

 any remains of either adult tsetse or pupae. 



An examination of the stomach contents of lizards revealed numerous kinds of 

 insects, but never of tsetse. The same is true of the nests of mason wasps. Tsetse 

 are not " fleshy " insects and are therefore unsuitable as a food for growing larvae. 



* Bull. Ent. Research, ii, p. 210. 



