PEACH INSECTS 267 



reduced by borer attacks are particularly liable to infestation 

 by bark-beetles, or shot-hole borers, which soon complete their 

 destruction. The peach-tree borer also infests the wild and 

 cultivated cherry, plum, prune, nectarine, apricot and certain 

 ornamental shrubs. 



The insect always passes the winter in the larval state. 

 Throughout its range the great majority of the wintering larvae 

 are less than one half grown, although a very few may be nearly 

 mature. Most of the larger larvae hibernate in their burrows 

 beneath the bark, but, as a rule, the smaller ones, those less than 

 one half grown, pass the winter on the bark curled up under a 

 thin silken covering or hibernaculum which protects them 



Fig. 230. — The peach-tree borer, full-grown (x 3j) . 



from the surrounding mass (jf gum. There are, however, ex- 

 ceptions in both cases ; nearly full-grown larvae are sometimes 

 found in hibernaculums and some of the smaller ones hibernate 

 in their burrows. In the extreme South the larvae remain in 

 their burrows, feeding nearly all winter, but in New York ac- 

 tivity is not resumed until the last of April or in May. At 

 that time the borers either continue the old burrows or start 

 new ones and soon excavate a cavity from one half to an inch 

 or more wide and two or three inches long just under the outer 

 bark in the inner bark and sap wood. A large quantity of gum 

 exudes from the burrows and collects in conspicuous masses 

 on the ground at the base of the tree. We have seen a peach 

 tree, only one and one half inches in diameter, support nine 

 borers nearly to maturity in a single season, and it is not un- 



