164 HABITS OF BIRDS. 
dens. A gentleman who was at the trouble of 
watching these birds, observed that the parents 
generally went from the nest and returned with in- 
sects from forty to sixty times in an hour, and that 
in one particular hour they carried food no fewer 
than seventy-one times. In this business the 
were engaged during the greatest part of the day. 
Allowing twelve hours to be thus occupied, a sin- 
gle pair of these birds would destroy at least 600 
insects in the course of one day, on the supposi- 
tion that the two birds took only a single insect 
each time. But it is highly probable that they 
often took more.’* 
Looking at the matter in this point of view, the 
destruction of insectivorous birds has, in some ca- 
ses, been considered as productive of serious mis- 
chief. 
From its sometimes eating grain and other seeds, 
“the rook,” says Selby, “has erroneously been 
viewed in the light of an enemy by most husband- 
men; and in several districts attempts have been 
made either to banish it or to extirpate the breed. 
But wherever this measure has been carried into ef- 
fect, the most serious injury to the corn and other 
crops has invariably followed, from the unchecked 
devastations of the grub and caterpillar. As ex- 
perience is the sure test of utility, a change of con- 
duct has in consequence been partially adopted; 
and some farmers now find the encouragement of 
the breed of rooks to be greatly to their interest, 
in freeing their lands from the grub of the cock- 
chafer (Melolontha vulgaris), an insect very abun- 
dant in many of the southern counties. In Nor- 
thumberland I have witnessed its usefulness in feed- 
ing on the larve of the insect commonly known by 
the name of Harry Longlegs (Tipula oleracea), 
* Anim. Biogr., ii., 282, 6th edit. 
