Pine bark borer, T o m i c u s p i n i Say 



1 Early work in wliitc pine bark 



2 Work in a more avh-anced stage 



Balsam bark borer, T o in i c u s b a 1 s a m ens Lee. 



3 Early work as shown on the surface of the wo(k1 



Turpentine bark beetle, D c n d r o c t o n u s terebrans Oliv. 



4 Work at the base of a tree, showing' main galh-ry with its pitch-lined 



walls 



776 



