INSECT DEPREDATIONS IN NORTH AMERICAN FORESTS. 79 



(3) By fellin<r the trees and placiiiir the unljarked loiifs in water. 



(4) By the adoption of a system of forest iiianaireiiient which will 

 provide for the prompt utilization of all trees which die from any 

 cause. 



PREVENTION OF LOSS FROM INSECT INJIRIES To NATIRAF, AND AlfTIFIClAI, 



KKPRonrCTION. 



The successful control of the insects which destroy or prevent the 

 normal development of natural reproduction is a far more dillicult 

 problem than that presented by other classes of insect injuries, l)ut 

 in this as in the others a great deal can be accomjilished toward pre- 

 venting the reduction of future supplies. 



^luch can be accomplished in nurseries and small plantations by 

 the adoption of the ordinary methods of controlling farm and or- 

 chard insects, but in the natural forests reliance nnist be placed 

 largely on systems of forest management which will bring about 

 unfavorable conditions for the work of the more important enemies. 

 (Hopkins, lOOGc.) 



T'tilizatiox oi" Immcnk .xnd Uksist.vnt V.vrietiks and Races of Trees. 



Certain individuals representing varietal or racial forms of trees 

 of a given sj)ecies are sometimes found to be either immune or de- 

 cidedly more resistant to the insects which are destructive or seri- 

 ously injurious to the life or wood of other individuals or varieties 

 of the same species. This fact suggests the importance of recogniz- 

 ing the well-known principle of imjirovement by selection. Thus, 

 selecting seed or cuttings froin such imuume and resistant trees for 

 artificial propagatioji, or taking <xvv:\i i)ains to leave sut-h tree-- in 

 connnercial or selection cuttings for natural reproduction, will un- 

 doubtedly be an important step toward providing against damage 

 and loss in the future, (Hopkin.s, VMmO, IdOla, VMlc. idOld.) 



rHF:VF.\T10N OF INSECT IN-FCRIKS To FoRFST I'RoDrc TS. 



The problem of artificial control and |U'evention of insect injuries 

 to forest i)roducts otters less ditticulties perhap> than that rcl:iiiiig 

 to nrany other branches of the general subject of forest -insect con- 

 trol. In most ca>es the principle of pievention i> the only one to l)e 

 considered, since the damage is done soon after the insects enter the 

 wood, and therefore it can not be repaired by destroying the enemy. 



Cm 1)1 I'ltoincTs. 



The proper degree of moisture found in the i)ark and wood of 

 newly felled trees, .saw logs, telegraph poles, posts, and like material, 

 cut in the fall and winter and left on the ground or in close piles 



