I 



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



1 Early work in white pine bark 



2 Work in a more advanced stage 



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Balsam bark borer, Tomicus balsameus Lec. 



3 Early work as shown on the surface of the wood 



Turpentine bark beetle, Dendroctonus terebrans Oliv. 



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



walls 



776 



