442 THE CANKER WORM. 



or suspending themselves by threads. They then 

 burrow in the soil to the depth of a few inches, and 

 become transformed. They are prevented from 

 spreading over any new tract of country very rap- 

 idly, by the wingless condition of the female. They 

 are exceedingly voracious during the period of their 

 growth, often entirely depriving the tree of leaves. 



To prevent ravages of the larvae we should stop 

 the female from ascending the tree. For this pur- 

 pose various methods have been adopted. Strips 

 of paper, covered with tar, have been used ; but the 

 necessity of a frequent application renders this only 

 a partial preventive. Boxes or troughs are some- 

 time fitted arQund the tree, so that the female is 

 obliged to make her way over them in ascending. 

 These are filled with a noxious fluid, or some liquid 

 which drowns the insects, and proves beneficial. 

 The Messrs. Claj)p, of Dorchester, Massachusetts, 

 used this remedy when their orchard was troubled, 

 and state that for a few evenings durmg the ascen- 

 sion of the insect the boxes became so completely 

 filled with moths that others travelled over the 

 bodies of their dead and dying companions. 



The most simple and efficient remedy is to place 

 a strip of zinc, four inches in width, around the tree, 

 so that the upper edge shall grasp the tree tightly, 

 and the lower stand out two inches from the trunk. 

 Then all the little interstices between the upper 

 edge and the tree should be stuff"ed to prevent their 



