THE GENUS DENDROCTONUS. 



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Fig. 75.— Balsam fir chips showing annual growth, indicating dates of death of spruce trees. 1, From 

 tree by dead spruce in cutting of about 1888; 2, from tree standing by dead spruce in old cutting of 

 about 1886; 3, from tree standing by dead spruce which showed the work of the eastern spruce beetle 

 (tree evidently died about 1888); h, from fir in blow-down of about 1871, which was followed by 

 another in about 1885-6; 5, from tree in blow-down cf about 1886; 6, from spruce standing by large 

 spruce tree which was broken by a storm of about 1886 (evidence was found in this tree that it was 

 living when felled and that it had been attacked, after falling, by the eastern spruce beetle; both 

 galleries and remains of beetles were found in the bark); 7, section of small suppressed spruce 

 about forty-five or fifty years old. All natural size. (Author's illustration.) 



