ROOK. 95 



alteration in the appearance of the leaves, or other parts, 

 above ground, and the Rooks seem to have learned by 

 experience how to select those plants which are the most 

 likely to afford them some recompence for the trouble they 

 take in grubbing them up, Mr. Jesse, in his instructive 

 Gleanings, says, " A gentleman once showed me a field 

 which had all the appearance of having been scorched, as if 

 by a burning sun in dry hot weather. The turf peeled from 

 the ground as if it had been cut with a turfing-spade, and 

 we then discovered that the roots of the grass had been eaten 

 away by the larvse of the cock-chafFer, which were found in 

 countless numbers at various. depths in the soil. This field 

 was visited by a great quantity of Rooks, though there was 

 no rookery within many miles of the neighbourhood, who 

 turned up, and appeared to devour the grubs with great 

 satisfaction. To prove their utility on other occasions, two 

 or three quotations from the Magazine of Natural History, 

 among many others, will suffice. A flight of locusts visited 

 Craven, and they were so numerous as to create considerable 

 alarm among the farmers of the district. They were, how- 

 ever, soon relieved from their anxiety, for the Rooks flocked 

 in from all quarters by thousands and tens of thousands, and 

 devoured them so greedily that they were all destroyed in 

 a short time. It was stated a few years ago, that there was 

 such an enormous quantity of caterpillars upon Skiddaw, that 

 they devoured all the vegetation on the mountain ; and 

 people were apprehensive they would attack the crops in the 

 enclosed lands ; but the Rooks, which are fond of hidi 

 ground in summer, having discovered them, in a very short 

 time put a stop to their ravages. 



The attempts occasionally made by man to interfere with 

 the balance of powers as arranged and sustained by Nature 

 are seldom successful. " An extensive experiment appears 

 to have been made in some of the agricultural districts on the 



