68 new york state Museum 



important effect upon many trees, lowering their vitality and pre- 

 sumably making conditions more favorable for insect attack. This 

 unfortunate condition may be accentuated in certain localities as, 

 for example, in southeastern Westchester county, by the abund- 

 ance of canker worms or other leaf feeders, since repeated destruc- 

 tion of the foliage would weaken the trees and, in the case of 

 developing leaves, might cause serious injury without attracting 

 much attention. Mr Henry Bird believes that he has detected a 

 connection between successive attacks by canker worms and in- 

 jury by the hickory bark beetle. 



Another factor which may be more important than many realize, 

 is forest fires or burnings. It is unfortunately the practice in 

 some communities to burn over pasture and woodlands rather 

 freely in the mistaken notion that benefit accrues. It is true that 

 such procedure is followed by a more vigorous growth of grass 

 and is generally accompanied by the destruction of leaf mold or 

 humus, not to mention the killing of numerous small trees and 

 injuring some of the larger ones. Moreover, this humus is a most 

 important ingredient in maintaining the fertility of the soil and 

 also of much service in protecting the roots of trees from ex- 

 cessively low temperatures, and by conserving moisture mitigates 

 in considerable measure, the severity of droughts. The greater 

 exposure to extreme temperatures and the additional severity of 

 droughts following the annual practice of burning, may well re- 

 sult in reducing the vitality of the trees and bringing about a 

 condition favorable to attack by borers. Such procedure is at 

 least indefensible from the standpoint of the forester and should 

 be condemned and avoided wherever possible. 



Generally speaking, we may expect the least trouble from in- 

 jurious insects where normal forest conditions prevail and the 

 trees as a whole are in a thriving condition. All practical measures 

 which result in the removal of sickly and dying trees and provide 

 better conditions for those allowed to remain will, in a general 

 way, reduce the liability of serious injury by insects. 



Remedial measures. A serious infestation, indicated by dying 

 trees or branches, can be controlled only by cutting out all badly 

 infested trees or portions of the same and destroying the bark 

 before the following June in order to prevent the grubs then in 

 the trees from maturing and changing to beetles which might an- 

 other season continue the work in previously uninfested trees. It 

 is particularly important to locate hickories which have died 



