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Bulletin American Museum of Natural History. [Vol. XXXVII, 



forms, trying to escape as the crackling of exploding grass-stalks comes 

 nearer, are carried high up into the air by the heat-waves. Here they are 

 preyed upon even by the bats, which in the Uele district are often attracted 

 to the fires in the night, just like swifts, swallows and other birds during the 

 day. But most of these insects are carried far away and alight undoubtedly 

 along the areas not destroyed by the flames. During this conflagration 

 bats are more plentiful in the neighborhood of rivers and such species as 

 formerly sought protection in the clusters of green leaves are suddenly forced 

 to look for other hiding places. At Faradje on the Dungu River, when the 

 trees were leafless, we observed that some bats not seen before about human 

 settlements came to the houses (Eptesicus faradjius and Glauconycteris 

 papilio). Even Laviafrons affinis which keeps to the open plains through- 

 out the year was more numerous in the trees about the post, and Taphozous 

 mauritianus likewise increased in numbers. 



Travellers that happen to camp, during this season, away from streams 

 and surrounded by the blackened soil might look in vain for bats. Shall 

 we wonder that Laviafrons, the species most ubiquitous over the equatorial 

 bushveldt, has learned to care little for cover and often hunts in bright 

 sunlight? Is it surprising that it feeds upon Coleoptera so large, that it 

 seizes them one by one? In its habitat tender insects that could be gathered 

 in rapid flight by the dozens may become scarce at times. 



Since their crepuscular and nocturnal habits of feeding have so vitally 

 influenced their structure, it is not without importance to state that, as a 

 rule, only those insects which disport themselves in full flight during at 

 least a few hours of darkness can make up their bill-of-fare. If we think 

 of the nuptial flights of termites, so abundant as to form a staple food even 

 for natives, of the clouds of mosquitos, of the numbers of roaches, crickets 

 and moths we realize that the supply exceeds the demand. From examina- 

 tions of their stomachs, we know that, besides Isoptera, Diptera, Orthop- 

 tera and Lepidoptera, many Hymenoptera, Hemiptera, and especially 

 Coleoptera, furnish a very large share of their sustenance. 



The food of each species consists undoubtedly of a great variety of 

 insects, a selection influenced probably by their seasonal abundance. In 

 the bushveldt their sudden appearance in great numbers is a very noticeable 

 feature. They seem to come and go with the growing and perishing of the 

 minor elements of vegetation, following well marked seasons. Yet in the 

 seasonless rain-forest such cycles of great profusion seem equally common. 



A few bats may gather at least a part of their food, such as small roaches 

 and spiders, in clambering about fruits and between the leaves. Of this 

 we suspect especially Pipistrellus nanus, which would be greatly helped 

 therein by its crawling propensities (p. 530). 



