94 CORVID.E. 



thousands of destructive grubs of the common cock-chaffer, 

 the wire-worms of several sorts, and, as mentioned by Mr. 

 Selby, the larvae also of the insect commonly known by the 

 name of harry-long-legs ; these, and probably many others 

 equally injurious to vegetation, are searched for and de- 

 voured with avidity, forming a very large proportion of the 

 food of this most numerous species. Early in the morning 

 Books visit meadow land while the grass is yet wet with 

 dew, to break their fast on worms and slugs, which the 

 moisture of that period induces to crawl forth. Later in 

 the day, they may be seen either searching newly-ploughed 

 ground for the various insects there exposed, or again visit- 

 ing pastures for other purposes. There they are accused 

 of destroying the grass by pulling it up by the roots ; " but 

 it has been stated, and I believe truly, that this is an error 

 arising out of the following circumstance : In searching 

 for grubs which are concealed in the earth, and supported 

 by eating the roots of the grass, the Rook pulls at the 

 blade of grass with its bill, and when the grass comes up 

 readily, the bird knows that there are under it insects 

 which have destroyed its roots, and in this way detects 

 them ; but if the blade of grass is firm, the Rook goes to 

 another part of the ground. In a field where grubs are 

 very abundant, the Rooks scatter the grass everywhere, so 

 as to give the appearance of having rooted it up, while 

 they have only exposed the depredations of the insects by 

 which the roots have been destroyed." The author of the 

 Journal of a Naturalist, speaking of the readiness with 

 which Rooks detect the places where grubs are sure to be 

 found, says, " I have often observed them alight on a pas- 

 ture of uniform verdure, and exhibiting no sensible appear- 

 ance of feathering or decay, and immediately commence 

 stocking up the ground. Upon investigating the object of 



