CHAPTER XVI 

 PROTECTION AGAINST INSECTS 



Extent of the Damage Caused by Insects. — The extent of 

 the annual loss due to insect depredations is more difficult to 

 accurately estimate than the fire loss : because the latter sta- 

 tistics (incomplete to be sure) are gathered by nearly all for- 

 estry organizations; while for the former equally detailed rec- 

 ords of losses are unheard of. General estimates made by 

 entomologists on the basis of observation and consultation 

 with other experts furnish the best available information. Dr. 

 A. D. Hopkins^ published in 1910, an estimate that the an- 

 nual loss in the United States from forest insect depredations 

 amounted to more than $100,000,000, or a reduction of 10 per 

 cent in the value of the annual output of forest products in the 

 rough. His estimate, when applied only to the value of the 

 standing timber killed and damaged, put the annual loss 

 based on a ten year average) at $62,500,000. These figures 

 do not include damage to manufactured forest products. 



It is probable that insects do more injury in the average 

 year than that caused by forest fires.^ 



Character of the Injury. — Insect depredations range from 

 the deforming, weakening or destruction of single trees up to 

 the killing of a large proportion of the timber in regions thou- 

 sands of square miles in extent.^ ^"'^ ^ The latter type of injury 

 may be readily observed but damage to single trees and small 

 gi-oups of timber often goes unnoticed, although in the aggre- 

 gate it must reach a tremendous total, and may exceed the 



loss in the large outbreaks. 



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