X THE SCOLYTID BEETLES. 



Detailed information on the species — Continued. Page. 



No. 10. The Black Hills beetle (Dendroctonus ponderosx Hopk.) 90 



Seasonal history 91 



Overwintering stages : : 91 



Activity of overwintered broods 91 



Generation 92 



Habits 93 



Economic features 95 



Evidences of attack 95 



Effects on commercial value of the wood 97 



Favorable and unfavorable conditions for the beetle 97 



Methods of control 98 



Basis of information 100 



Bibliography 101 



No. 11. The Jeffrey pine beetle (Dendroctonus jeffreyi Hopk.) 101 



Seasonal history 102 



Overwintering stages 102 



Activity of overwintered broods 102 



Habits 102 



Methods of control 103 



Basis of information 103 



Bibliography 103 



No. 12. The eastern larch beetle {Dendroctonus simplex Lee.) 103 



Seasonal history. . . 104 



Economic features 105 



Methods of control 105 



Basis of information 105 



Bibliography 106 



No. 13. The Douglas fir beetle (Dendroctonus pseudotsugse Hopk.) 106 



Seasonal history 107 



Overwintering stages 107 



Activity of overwintered broods 107 



Generation. 108 



Habits 108 



Economic features 109 



Evidences of attack 109 



Effects on commercial value of the wood Ill 



Favorable and unfavorable conditions for the beetle Ill 



Methods of control Ill 



Basis of information 113 



Bibliography 114 



No. 14. The eastern spruce beetle (Dendroctonus piceaperda Hopk.) 114 



Seasonal history 114 



Overwintering stages 114 



Activity of overwintered broods 115 



Generation 117 



Habits 117 



Economic features 120 



Character of attack and injury 120 



Extent of depredations 122 



Evidences of attack 122 



Effects on commercial value of the wood 123 



Favorable and unfavorable conditions for the beetle 123 



