n 



through the tree- tops has a very different effect: 

 the twigs and bark are burned off and the 

 pitches are boiled through the exterior of the 

 trunk and the wood fortified against all sources 

 of decay. This preservative treatment often 

 gives long endurance to fire-killed timber, espe- 

 cially when the trees killed are yellow pine or 

 Douglas spruce. Many a night in the Rocky 

 Mountains my eager, blazing camp-fire was 

 burning timber that forest fires had killed forty 

 and even sixty years before. 



In forest protection and improvement the 

 insect factor is one that will not easily down. 

 Controlling the depredations of beetles, borers, 

 weevils, and fungi calls for work of magnitude, 

 but work that insures success. This work con- 

 sists of the constant removal of both the in- 

 fected trees and the dwarfed or injured ones that 

 are susceptible to infection. Most forest insects 

 multiply with amazing rapidity; some mother 

 bark-beetles may have half a million descend- 

 ants in less than two years. Thus efforts for 

 the control of insect outbreaks should begin at 

 once, in the early stages of their activity. A 



187 



