18 INSECTS INJURIOUS TO THE APPLE. 



it doubtless remains inactive until the following spring. 

 During the uext season it attains about half its growth, 

 still living on the sap-wood, where it does great damage, 

 and when, as often happens, there are several of these 

 borers in a single tree, they will sometimes cause its death 

 by completely girdling it. After another winter's rest, the 

 larva again becomes active, and towards the end of the 

 following season, when approaching maturity, it cuts a cylin- 

 drical passage upwards, varying in length, into the solid 

 wood, afterwards extending it outward to the bark, some- 

 times cutting entirely through the tree, at other times turn- 

 ing back at different angles. The upper part of the cavity 

 is then filled with a sawdust-like powder, after which the 

 larva turns round and returns to the part nearest the heart 

 of the tree, which portion it enlarges by tearing off the 

 fibres, with which it carefully and securely closes the lower 

 I)ortion of its gallery, so as to protect it effectually from the 

 approach of enemies at either end. Having thus perfected 

 its arrangements, it again turns round so as to have its head 

 upwards, when it rests from its labors in the interior of the 

 passage until the following spring, when the mature larva 

 sheds its skin and discloses the chrysalis. In this condition 

 it remains about two or three weeks, when the perfect beetle 

 escapes. At first its body and wing-cases are soft and flabby, 

 but in a few days they harden, when the beetle makes its 

 way tlirough the sawdust-like castings in the upper end of 

 the passage, and cuts with its powerful jaws a smooth, 

 round hole through the bark, from which it escapes. 



The larva (Fig. 3, a) is of a whitish color, with a round 

 head of a chestnut-brown, polished and horny, and the jaws 

 black. It has also a yellow horny-looking spot on the first 

 segment behind the head. It is without feet, but moves 

 about in its burrows by the alternate contraction and ex- 

 pansion of the segments of its body. When full grown it is 

 over an inch in length. 



The color of the chrysalis (Fig. 3, b) is lighter than that 



