Pimpla, Cremastys, and Aleiedes, or a closely allied genus. ' No 

 doubt it is to these friendly insects that the sudden decrease in 

 the numbers of the leaf -roller larvae so often noticed' is to be at- 

 tributed. 



REMEDIES. 



It is difficult to prevent the depredations of this insect upon 

 young apple-trees on account of the concealed position of the 

 larva, and its hajDit of attacking the young terminal leaves. The 

 application of the arsen\p€Cr poisons is probably as promising as 

 any general remedy; but I believe that the most effective pre- 

 ventive of nursery injury is that of hiring boys to crush the 

 larvge. This is not such an endless task as would at first appear; 

 and if the first brood of larvae are thus destroyed, the outlay will 

 be tenfold repaid. That it is eminently practicable on a large 

 scale has been demonstrated the past season by a leading Illinois 

 nurseryman who found that the expense of once going over a badly 

 infested field did not exceed one dollar per acre; and that the out- 

 lay was abundantly repaid by the continued vigorous growth of 

 the trees. In a recent letter the gentleman informs me that he 

 intends continuing the practice "more vigorously in the future 

 than in the past." 



Mr. Smith has recommended light traps for attracting the moths 

 in cranberry fields; and probably the same means could be em- 

 ployed to lessen the number of the moths in nurseries, especially 

 in early ^ring, when the hibernating moths are abroad for the 

 purpose of depositing their eggs. 



