Beneficial Insects . 



Most of the injurious insects are the hosts of 

 parasites, minute insects which go far toward holding them 

 in check. Little is knovm. of the different species or life 

 histories of these parasites. Complete eradication of in- 

 jurious inseccs through their agency cannot be expected. 



Considerably moro is known of the predaceous in- 

 sects. One, a bright green or blue beetle (Trogosita vires - 

 cens) 2/8 to 3/4 of an inch in length, preys on many of the 

 bark-borer adults while the larvae of a greyish white c^lor 

 with a chining black head preys on the grubs of various bark 

 beetles, and may often be found under the bark of infested 

 trees. 



Three species of a predaceous Clerid beetle are 

 also foiind on conifers. The larvae are slender pink griibs 

 found under the bark and are supposed to prey on destructive 

 and injurious species. The adults are swift running, ant- 

 like beetles, hiding in the crevices of the bark of an in- 

 fested tree. On approaching a tree the 37 may often be heard 

 leaving viith a distinct click as they fly. These adults 

 watch for Dendroctonus emerging from the exit holes, which 

 they rapaciously devour. 



Many species of Rove Beetles, slender, swift run- 



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