Destruction of Insects 299 



attention so much taken up with one another, is another of 

 the marvels in the bird's economy which, perhaps, we shall 

 never thoroughly understand. 



Of course, it is well enough known, nowadays, that 

 such birds as Swifts do not habitually fly about with mouth 

 a-gape, but that they snap up individual insects as they go 

 along. When fishing in the evenings, however, where 

 swarms of " up-and-down flies " were dancing over the 

 water, I have watched Swifts (and Swallows too), dart, open- 

 mouthed, through a dense column, " browning the flock," 

 as it were, and not singling out any particular insects. 

 Swallows do this in a gentlemanly way, gliding through the 

 throng, and no doubt filling their bills, but doing small 

 damage with their wings ; but the Swift always most 

 eagerly upon the feed at this hour charges the crowd 

 without mercy, his wings going like the sails of a windmill, 

 and the destruction they cause amongst the insects must 

 be many times in excess of what are actually devoured. 

 The result may sometimes be traced in a wide line of 

 maimed and dead flies, scattered on the water in the direc- 

 tion of the line of flight. The audible " snap " with which 

 a large insect, like a May-fly, is engulfed in the capacious 

 mouth of a Swift, is a familiar sound to many contemplative 

 persons. I have, also, seen quite large moths taken, Cara- 

 drina cubicularis, so often disturbed from hay-fields, being 

 an especial favourite. 



Almost everywhere throughout the country the Swift is, 

 or has been at some time, associated in the popular mind 

 with the spirits of darkness. In some places it has been 

 called simply " devil," or " devil's bird," in others it is 

 known as a " screaming devil," a " deviling," or " little 

 devil," and so on. One probable origin of such association 

 has been thus graphically described by the late Mr Henry 

 Stevenson 1 : 



" There is another period, too, when the Swift almost in- 

 variably appears abroad, though previously, perhaps, unseen 

 for hours. The air is hot and stifling, and a sudden gloom 

 creeps as it were over the earth and sky. An almost painful 

 1 Birds of Norfolk, vol. i., p. 343. 



