THE PINE INVESTIGATION. 



419 



Virginia, and probably not more than one in the Transition 

 and Canadian zones. 



CHARACTER OF INJURY. 



Harris 1 says that "their depreditions interrupt the descent of 



Fig. LXXVIII---Galleries and mine of Dendroctonus terebrana; a, primary and second- 

 ary gallery; b, social larval cavities; c, side entrances; d. inner bark. 



1 Insects Injurious to Vegetation, pp. 85-86. 



