115 



the borders of, the fly areas of Damba and Bugalla Islands," showed 

 no trace of Tsetse-fly remains in any instance. 



In order to determine the nature of the food of vertebrates, and 

 especially of birds, investigators have a choice of several methods. 

 Among these the following may be mentioned : simple observation, in 

 the open, of the food of the adults or their young ; experiments and 

 observations in captivity ; microscopical examination of dejecta found 

 in burrows, holes in treas, caves, nests, &c. ; and, finally, microscopical 

 analysis of the stomach contents (remains of insects and vegetable 

 matter) of the subjects of investigation after being shot. 1 



Attention should be paid, not only to vertebrates which prey upon 

 perfect insects, but also to those which may feed upon pupae, and 

 especially to scratching birds (Gallinaceae), such as guinea fowl, 

 " pheasants," francolins, &c., which are frequently found in great 

 abundance in the fly-belts. 



Mr. LI. Lloyd, who examined the crop contents of ten guinea fowl 

 in the Luangwa Valley, Northern Rhodesia, writes (90) : ' The crop 

 of each was filled with vegetable matter, small bulbs, roots and flower 

 buds. In three only were insects found, and these were in very small 

 numbers. The following insects were observed in them : small 

 Staphyline beetles, coleopterous larvae, and lepidopterous larvae. No 

 pupae of any kind were recorded. From this it is clear that the guinea 

 fowl is a vegetable feeder, eating insects when it finds them in its search 

 for vegetable food. In the case of G. morsitans the majority of the 

 pupae are placed in positions which would be inaccessible to these birds, 

 though a few could be easily found. Doubtless a few of the pupae are 

 eaten by guinea fowl, but the number must be so small that the bird 

 cannot be considered to act as a control." Similar investigations 

 into the crop contents of the different francolins (Francolinus and 

 Pternistes) would be of interest. 2 



Predacious Arachnids. A study of the bionomics and food of 

 African arachnids would possibly lead to interesting discoveries. It 

 appears that spiders do not prey upon any species in particular, but 

 capture and suck the juices of all arthropods that they are able to 

 overpower. In the case of certain species that have been observed to 

 prey upon Tsetse-flies, practically all belong to the Family Salticidae 

 (jumping spiders), the species of which do not spin webs, but lie in 



1 Systematic investigations of this kind have already been carried out in 

 different countries. In the United States, where the Bureau of Biological Survey 

 of the Department of Agriculture has, for years past, been enquiring into the 

 nature of the food of American birds, the collecting of stomachs and the examina- 

 tion of their contents are conducted in the most systematic manner. Between 

 1885 and 1915 some 150 memoirs/dealing with the economic value of birds, were 

 published by the Biological Survey. In England, too, Mr. Walter E. Collinge, 

 a well-known biologist, has made a scientific study chiefly by examination of 

 the stomach contents of the nature of the food of a large number of British 

 birds. The results of this investigation have been published in various works 

 and brochures, among which the volume entitled The Food of some British 

 Wild Birds (1913) deserves special mention. 



Lastly, in India, the nature of the food of 1 10 Indian birds has been investigated 

 by Messrs. C. W. Mason and H. M. Lefroy, and the results of the examination 

 of 1,330 stomachs have been recorded in a report published in 1912 by the Indian 

 Department of Agriculture, under the title The Food of Birds in India. 



2 It seems to us that it would be well to continue these investigations ; the 

 examination of a larger number of guinea-fowl crops, in other fly-belts, would 

 perhaps yield different results. 



