96 



THE SCOLYTID BEETLES. 



1 :■' -U 







Fig. 56.— Work of the Black Hills beetle in the Black Hills National Forest: A, Small freshly at- 

 tacked fine tree, showing pitch tubes. B, Marks of primary galleries on surface of wood when 

 bark is removed. C, Freshly attacked tree, showing pitch tubes; near tree not attacked. 

 D, Dead tree, showing where outer bark has been removed by woodpeckers. (Author's illus- 

 tration.) 



