THE PINR INVESTIGATION. 413 



ed in this report, which have occurred from time to time in this 

 country and Europe during the past century, we must expect to 

 see it repeated in the future either by this, or some other de- 

 structive bark beetle. 



CHARACTERISTIC FEATURES OF INJURY TO FOREST AND SHADE TREES 

 BY DENDROCTONUS FRONTALIS . 



The characteristic features of the work of the destructive 

 pine bark beetle by which its presence may be detected are as 

 follows: 



First. Turpentine or gum flowing from numerous wounds 

 in the bark, and small globular masses of turpentine adhering 

 to the surface on the upper portion of the trunks of living 

 trees. 



x.x. 



Fig. LXXII, a. Galleries of Dendroctonus frontalis in living tree, wound healing. 



Second. Groups of dying trees scattered through a pine or 

 spruce forest ; the leaves gradually changing from green to 

 yellow, then to red and reddish brown, and remaining on the 

 twigs for a long time after they are dead and dry. 



Third. The base and lower portion of the trunk of standing 

 trees remain alive for some weeks or months after the top is 

 dead. 



Fourth. Upon removing the bark from the upper part of the 



