180 THE COMMON ROOK. 



It is but simple justice to these often-censured 

 birds, to mention the service that they at times 

 perform for us in our pasture lands. There is no 

 plant that I endeavour to root out with more per- 

 sistency in these places than the turfy hair-grass 

 (air a ccespitosd). It abounds in all the colder parts 

 of our grass lands, increasing greatly when undis- 

 turbed, and, worthless itself, overpowers its more 

 valuable neighbours. The larger turfs we pretty 

 well get rid of ; but multitudes of small roots are 

 so interwoven with the pasture herbage, that we 

 cannot separate them without injury; and these 

 our persevering rooks stock up for us in such 

 quantities, that in some seasons the fields are 

 strewed with the eradicated plants. The whole 

 so torn up does not exclusively prove to be the 

 hair-grass, but infinitely the larger portion con- 

 sists of this injurious plant. The object of the 

 bird in performing this service for us, is to obtain 

 the larvae of several species of insects, underground 

 feeders, that prey on the roots, as Linnaeus long 

 ago observed upon the subject of the little nard 

 grass (nardus stricta). This benefit is partly a 

 joint operation : the grub eats the root, but not 

 often so effectually as to destroy the plant, which 

 easily roots itself anew ; but the rook finishes the 

 affair by pulling it up to get at the larvae, and 

 thus prevents all vegetation ; nor do I believe 

 that the bird ever removes a specimen that has not 

 already been eaten, or commenced upon 5 by the 

 caterpillar. 



