292 CORVID^l. 



by agriculturists is a question which general opinion seems 

 to have settled by considering that the damage, though 

 often great, is much more than outweighed by the ser- 

 vices rendered in the destruction of millions of grubs 

 of the cockchafer, chovy, the several species of wireworm, 

 and the larvae of crane-flies, commonly called harry-long- 

 legs ; these, and many others equally injurious to vegetation, 

 are eagerly sought and devoured, forming a very large pro- 

 portion of the food of this most numerous species. Early in 

 the morning Rooks visit meadows while the grass is yet wet 

 with dew to break their fast on worms and slugs. Later in 

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

 land for the various insects there exposed, or again visiting 

 pastures for other purposes. They have been accused of 

 destroying the grass by pulling it up by the roots ; but this 

 is an error. The tufts of grass or other plants, so often 

 found withered on the surface, have already been destroyed 

 by the grubs which live in the soil having eaten into their 

 roots, as is evident on examination. The plants retain their 

 position in the ground and for some time their verdure, but 

 are quite loose and can be removed almost by a touch. The 

 Rooks merely pull them up in the act of getting at the 

 authors of the mischief. The grass that is uninjured is left 

 growing. In what way the birds first detect the presence of 

 grubs in the ground is not known to us. Some think by 

 actual experiment : others by the altered appearance of the 

 plant ; but the result is certain : large patches of a pasture 

 are often thus probed, and, though the damage already done 

 be considerable, further injury, especially that which would 

 follow from the grubs attaining maturity and propagating 

 their kind, is completely prevented.* The utility of 

 Rooks on other occasions has also been declared. Many 

 years ago, it is said (Mag. Nat. Hist. vi. p. 143), a flight of 

 locusts visited Craven, and their numbers created consider- 

 able alarm among the farmers of the district. The Rooks, 

 however, flocked in from all sides by thousands and devoured 



* The Rook however is not the only bird which confers this benefit. Par- 

 tridges destroy a vast number of grass-eating grubs. 



