obtained regarding them."" The Mountain Pine Beetle generally 

 kills about 95 per cent of sugar pines, the Western Pine 

 Beetle about 80 per cent of yellow pines, the Jeffrey Pine 

 Beetle about 80 per cent of Jeffrey pines and the Mountain 

 Pine Beetle about 60 per cent of lodgepole pines. The in- 

 sects killing firs and cedars are not very well known, espe- 

 cially the percentage killed by each species of insect. 



These tables sho?/ that the beetles killing pines 

 are entirely different from those killing firs and cedars; 

 therefore, an infestation in pines can be treated without 

 reference to infected firs or cedars. Infestations of the 

 Western Fine Beetle will not affect sugar pine, but the Moun- 

 tain Pine Beetle in sugar pine will attack yellow pines. The 

 Red turpentine Beetle attacks all pines, but the Jeffi'ey Pine 

 Beetle only Jeffrey and yellow pine. The Doiiglas Fir Beetle 

 does not, as far as now known, attack pines. 



The depredations of all these beetles belonging 

 to the genus Dendroctonus (Tree killers) are generally on 

 mature trees. Young growth is attacked and killed by a dif- 

 ferent group -of beetles. . Thus, the groiip of engravers be- 

 longing to the genus Ips kill poles and saplings and tops 

 of mature pine trees. Another group belonging to the Eccop- 

 togaster kill young white and Douglas firs, and tops of matu. 



See, "B*ark Beetles of the Genus Dendroctonus' 7 , by Dr. A. T > 

 Hopkins, Bui. 83, Pt . 1 of the Bureau of Entomology. 



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