CO^'TEKTS. IX 



Detailed inJormation on the species— Coutinued. 



No. 4. The southern pine beetle (Dendractonus/ronia/i'sZimm.) 56 



Seasonal history. ^ 57 



Northern section -. 57 



Overwintering stages 57 



Activity of overwintered broods 57 



First generation 58 



Second generation 59 



Third generation 59 



Fourth generation 59 



Fifth generation 60 



Periods of destructive attack 60 



Southern section 60 



Habits 60 



Economic features 63 



Evidences of attack : ' 64 



Effects on commercial value of the wood 65 



Favorable and unfavorable conditions for the beetle 65 



Methods of control 67 



Basis of information 70 



Bibliography. 72 



No. 5. The Arizona pine beetle {Dendroctonus arizonicus Hopk.) 72 



Seasonal history 72 



Basis of information •. 73 



Bibliography 73 



No. 6. The smaller Mexican pine beetle {Dendroctonus mexicanus Hopk.). . 74 



Bibliography 75 



No. 7. The larger Mexican pine beetle (Dendroctonus pca-allelocolHs Chap. ) . 75 



Bibliography 75 



No. 8. The Colorado pine beetle {Dendroctonus approximatus Dietz ) 76 



Seasonal history 77 



Overwintering stages 77 



Activity of overwintered broods 77 



Generation 77 



Habits 78 



Economic features - 78 



Basis of information - 79 



Bibliography - 80 



No. 9. The mountain pine beetle {Denjdroctonus montkolx Hopk.) 80 



Seasonal history 81 



Overwintering stages 81 



Activity of overwintered broods - 81 



Generation - 82 



Habits 83 



Economic features 84 



Evidences of attack - 84 



Effects on commercial value of the wood 85 



Favorable and unfavorable conditions for the beetle 86 



Methods of control • - 87 



Basis of information 89 



Bibliography 9" 



