THE PINE INVESTIGATION. 



417 



r^ntra'isegment 86 ?" 



prefers to enter the bark of dying trees and that of the stumps 

 of recently felled ones, and will attack healthy trees only 



when it does not find those offering 

 more favorable conditions. 



It shows a decided preference for 

 the living bark at the base of trees 

 and stumps, and even the exposed 

 roots, in which to excavate its brood 

 galleries. It rarely breeds in the 

 bark of logs on the upper portion of 

 the trunk of standing trees. 



Harris 1 says that it lays its eggs in 

 the bark ot the trunk and branches 

 of the pitch and other pines. Among 



Fig. i.^v-Dendroctonu 8 tere. a large series of collectings and ob- 



servation notes with reference to this 

 bark beetle, in all of our native pines 

 and in the Norway spruce, I have no 



record of it occurring in the bark of the upper part of a standing 

 tree, and but one or two of its occurrence in the bark of felled 

 trees. It has almost invarabiy occurred at the base of living 

 or dying trees or stumps, and often in the roots beneath the 

 surface of the ground. 



The parent beetles select a crevice in the bark and excavate 

 the main entrance to the inner bark through which the gallery 

 is extended. If the bark is full of turpentine, progress is slow, 

 and often a great quanity of this resinous substance is pushed 

 out, frequently forming masses as large as a walnut at the 

 mouth of the entrance. 



The primary gallery is usually extended longitudinally, both 

 above and below the main entrance, seldom in a lateral direc- 

 tion, although the secondary or branching galleries may do so. 

 Twenty to forty eggs are placed in a mass along the sides of 

 the main or secondary galleries, and when the larvae emerge 



1 Insects injurious to vegetation. Flint Ed. p. 85. 



