THE COCK-CHAFER, 237 



Mouffet informs us that, in'the month of February, 

 1574, there were such multitudes of them in the 

 western parts of England, that those which fell into 

 the river Severn completely clogged the water- 

 wheels of the mills *. 



The rooks and gulls devour immense numbers of 

 the grubs of this destructive insect, by which they 

 render a most essential service to mankind, and 

 great care ought to be taken to cherish and protect 

 them. The sole employment of rooks, for nearly 

 three months in the spring of the year, is to search 

 for insects of this sort for food, and the havoc that a 

 numerous flock makes among them must be very 

 great. 



A cautious observer, having found a nest of five 

 young jays, remarked that each of these birds, 

 while yet very young, consumed at least fifteen of 

 these full-sized grubs in a day ; and averaging their 

 sizes, it may be said that they each consumed 

 twenty : this for the five makes a hundred : and, if 

 we suppose the two parents to devour between 

 them the same number, it appears that the whole 

 family consumed about two hundred every day. 

 This in three months amounts to twenty thousand. 

 But as the grub continues in the same state for four 

 years, this single pair, with their family alone, with- 

 out reckoning their descendants after the first year, 

 would destroy as many as eighty thousand grubs, 

 Now, supposing that forty thousand of these may 

 be females, and that each female lays, as is the case. 



* Phil. Tua. ci. xliv. 



