INSECT ENEMIES OF WESTERN FORESTS 



141 



Figure 63. — Tunnels of the Jeffrey pine beetle on the inner bark surface of 



Jeffrey pine. 



Trees are attacked most frequently in July or August. Eggs are 

 laid, and some of the insects reach the new adult stage by winter. 

 Parent adults, larvae, and new adults spend the winter under the 

 bark. In the spring, development continues, most of the new 

 broods emerge in July and August, and thus there is ordinarily 

 only one generation a year. 



Either peeling the bark from infested trees before new adults 

 form, or burning it, will kill the Jeffrey pine beetle. Methods used 

 for the control of the western pine beetle are usually employed for 

 this species also. 



The lodgepole pine beetle (Dendroctonus murrayanae Hopk.) 

 develops in large numbers in freshly cut stumps and attacks the 

 base of old, weakened lodgepole pine in eastern Washington, Idaho, 

 Montana, Wyoming, and Colorado. Ordinarily not an aggressive 

 enemy, it occasionally kills overmature lodgepole pines left stand- 

 ing after tie operations, timber sales, or other cuttings. Fortu- 



