THE SWALLOW. 173 



although they were literally crammed with 

 drones, there was not a vestige of a working 

 bee. We learn from Wilson 1 that in the United 

 States bees constitute part of the ordinary food 

 of the Purple Martin ; and the Sand Martin has 

 been observed to prey upon the common wasp. 

 Gilbert White remarked that both Swifts and 

 Swallows feed much on little Coleoptera, as well 

 as on gnats and flies, and that the latter birds 

 often settle on the ground for gravel to grind 

 and digest their food. At certain times in the 

 summer he had observed that Swifts were 

 hawking very low for hours together over pools 

 and streams, and, after some trouble, he ascer- 

 tained that they were taking Phryganece, Ephe- 

 mercz, and Libellulce (Cadew-flies, May-flies, and 

 Dragon-flies), that were just emerged out of 

 their aurelia state. The indigestible portions of 

 their food are rejected in the shape of small 

 pellets, just as with the birds of prey. Apropos 

 of these observations, Mr. J. H. Gurney, in 



1 " American Ornithology." 



