CHAPTER VIII 

 PROTECTION FROM OTHER INJURIOUS AGENCIES 



Protection from Insects 



Next to fire the greatest damage to forests is done by 

 insects. Sometiines the depredation by insects manifests 

 itself in a wide-spread Invasion in which a large percent- 

 age of the most valuable trees are killed over hundreds of 

 square miles. Such outbreaks have unquestionably oc- 

 curred from time immemorial. It is probable that in 

 some cases insects are responsible for the practical destruc- 

 tion of whole forests. In recent years there have been 

 numerous great invasions in different forest regions of 

 the country, causing damage to the extent of millions of 

 dollars. More often the work of insects is less conspicu- 

 ous, and for this reason the importance of protecting 

 forests from this source of damage has not been fully ap- 

 preciated by the public, nor even by practising foresters. 

 There are at all times throughout every forest hordes of 

 insects at work on the trees. Some of these are relatively 

 harmless, but there are nearl)' always some injurious 

 species at work. It is very common to find trees dying 

 here and there, individually or in groups, as a result of 

 the work of insects. The aggregate loss from these scat- 

 tered injuries is enormous. 



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