Insect and Disease Control 229 



in both the larval or grub stage and the adult or beetle 

 stage and, by extending their burrows in great numbers 

 between the bark and sapwood, destroy that vital part of 

 the tree known as the cambium. As a rule, sound, vigorous 

 bark is not attacked, injury being confined to such trees as 

 have had their normal health impaired by some other agency. 

 Cases are not unknown, however, in which the beetles have 

 multiplied greatly in diseased and dying wood and have 

 then extended their attacks to near-by healthy trees, caus- 

 ing extensive loss." 



The presence of these insects in peach trees is indicated 

 frequently by the appearance on infested limbs of a mass of 

 gum or gelatinous substance which exudes from each "pin- 

 hole" where an insect is working, or under some conditions 

 the gum may not appear, but the small, circular, clearly cut 

 holes can be readily seen. The weakened, unhealthy ap- 

 pearance of an infested branch is also likely to attract at- 

 tention. 



Appearance. 



The adult is a beetle about -^ Inch in length and of a 

 dark brown or black color. The larva when full grown is 

 also about -^ inch in length, white in color, with a reddish 

 head. It is in this form that most of the injury is done. 



Distribution. 



This bark-beetle occurs in practically all of the United 

 States east of the Mississippi River, and in many localities 

 to the west, though it is not known to have occurred in the 

 Pacific coast states ; it is also found in Canada. 



