4: DEPARTMENT CIRCULAR 411, U. S. DEPT. OP AGRICULTURE 



PINE SLASH 



The pines suffer more than any other group from the attack of 

 bark beetles. It is not surprising, therefore, that pine slash should 

 be viewed with the greatest suspicion as a forest menace. Upon 

 study, however, the danger loses much of its alarming aspect. 



WHITE PINE IN THE NORTHEAST 



The only really serious bark-beetle enemy of the white pine {Pinus 

 strobus) which breeds in slash in the Northeast is the Pales weevil (Hy- 

 lobius pales Herbst). Studies by Peirson (9) indicate not only that 

 this beetle breeds in stumps and cull logs but that the adult is also 

 strongly attracted into slash areas for the purpose of feeding. It 

 kills great quantities of small reproduction by gnawing off the bark 

 until girdling results, and is frequently the limiting factor in obtain- 

 ing white-pine regeneration. 



No satisfactory method of control has yet been devised. Burn- 

 ing the bark of cull logs and thoroughly charring the stumps, or 

 peeling the bark of logs and stumps (both of which are difficult and 

 expensive processes), may lessen the damage to some extent, but will 

 have no effect in lessening the attractive influence of the slash, which 

 is," after all, probably the greatest source of danger. R. T. Fisher, 

 in his experimental silviculture on the Harvard forest, has found that 

 the only practical m.ethods of preventing serious losses are (1) ob- 

 taining such an abundance of reproduction through reproduction 

 cuttings that there are still enough seedlings left to produce a stand 

 after the destruction wrought by the weevil, and (2) clear cutting, 

 and subsequent planting after an interval of three 3^ears. 



RED PINE AND WHITE PINE IN THE GREAT LAKES REGION 



Graham (^) reports that insect species that normally breed in the 

 slash of the red pine {Pinus resinosa) and white pine (P. strobus) in 

 the Great Lakes region have seldom been observed attacking or kill- 

 ing healthy trees. The insects responsible for the few exceptions to 

 this rule are all found breeding in the stumps and larger parts of the 

 slash. 



The bark beetle Dendroctonus valens Lee. May occasionally kill trees, 

 and is one of the most common of the species that breed in fresh pine 

 stumps. It is almost never found breeding in parts of the tree more 

 than 6 or 8 feet above the ground. All recorded cases of injury 

 caused by this beetle to a standing tree have been associated with 

 the attractive influence of logging operations, windfalls, fu'es, or logs 

 in storage. 



Several species of Ips occasionally kill trees and these, like the 

 Dendroctonus beetles, usually breed most abundantly in the larger 

 parts of the slash. The most common offenders of this group are 

 Ips pini Say, a primary pest of red and white pines, and /. calligrapJius 

 Germar, which breeds in white pine. In the light of present knowl- 

 edge it is safe to say that in the Lake States only the larger parts 

 of the trees constituting pine slash have any entomological signifi- 

 cance so far as living standing trees are concerned. Just how impor- 

 tant an entomological factor these parts are can not be said, but it is 

 certain that the stumps provide the most favorable breeding places. 



