THE WESTERN PINE BEETLE 





Figure 7. — Death to the western pine beetle. An infested ponderosa pine has 

 been felled, limbed, the bark peeled from the upper portion of the trunk, piled 

 along the trunk, and burned. This is the last step in a fell-peel-burn direct- 

 control project. 



and then the entire pile is burned. Because of the forest-fire hazard 

 during the summer months, the fell-peel-burn method is best applied 

 from October 1 to May 1, depending on conditions for burning and 

 working. It has not been economically feasible to rely entirely on 

 this method of control because of the high costs and temporary bene- 

 fits ; however, direct control measures are still practicable, and under 

 careful supervision it is possible to effect drastic reductions in pine 

 beetle populations on a control area for one or more years. 



When the western pine beetle is controlled through logging of in- 

 fested trees, part or all of the control costs are offset by the sale of the 

 salvaged lumber. By this method the infested tree must be removed 

 from the woods before the beetles emerge and the broods must be 

 killed by placing the logs in ponds or by burning the slabs before 

 emergence takes place. The rapid blue-staining of the sapwood soon 

 after attack, with the resulting heavy degrading of the lumber from 

 infested trees, has discouraged the extensive salvage of these infested 

 trees as a control measure. This prejudice against blue-stained lum- 

 ber is unwarranted, because the fungi that cause the staining do not 

 affect the strength or lasting qualities of the wood. 



Indirect Control 



The most promising methods of combating the western pine beetle 

 are improved forest-management practices. Recent research by forest 

 entomologists has shown that in any ponderosa pine stand certain 

 types of trees are highly susceptible to attack. It has been found that 

 trees declining in vigor, of slow growth and poor thrift, or top-killed ; 



