2 INSECT DAMAGE IN THE NATIONAL PARKS. 



EXTENT OF THE DAMAGE. 



The extent of the damage to the forests by insects through the 

 accumulation of dead timber and the djang of matured trees over 

 large areas is vastly greater than the general observer would suppose. 

 In fact, the dead and fallen timber is so common in all forests that 

 it has heretofore been recognized as a natural and inevitable condi- 

 tion. Large areas of insect-killed timber have been charged to fire 

 Avithout further thought or examination to determine the real cause. 

 Fallen tiniber has been attributed to storms, and scattering dead 

 trees to old age. 



During the present year a reconnaissance was made of typical 

 sections in one of the national forests, Avhere there was no evidence 

 that destructive forest fires had occurred during the past 20 years. 

 It was found that the standing and fallen dead yellow pine that 

 had died within that period amounted in board feet to nearly half as 

 much as that which was then living, and of the sugar pine and 

 Douglas fir there was one-fourth as much dead as was then living, 

 and every dead tree examined in the estimate showed evidence that 

 it had been killed b}" insects. 



In the Black Hills National Forest of South Dakota over one-half 

 of the timber died within a period of about 10 years. In Oregon 

 and Montana nearly all of the larger pine died within a few years 

 on areas of a few hundred acres to 100,000 acres or more. These 

 together Avith many other examples of extensive dying of timber 

 have been investigated and found to be caused primarily by insects. 

 Investigations have also demonstrated be3"ond question that a vast 

 amount of timber is killed by insects every 3'ear within the forested 

 areas of the Rocky Mountain and Pacific Coast regions. Further- 

 more, the accumulation of this dead timber and fallen debris is a 

 menace to the living, because it furnishes fuel for destructive forest 

 fires. The losses from insect depredations are thus augmented by 

 fires. 



The extent of damage to the forest and other trees of the national 

 parks has not been estimated and, with the exception of investigations 

 conducted in the Yosemite and Glacier Parks, we do not have much 

 direct information as to the damage already done. It is plain to us, 

 however, that the ger.eral conditions are not different from ihose 

 which prevail throughout the regions in which the parks are located 

 and in Avhich the destructive species of insects are known to occur. 



The amount of damage in the parks must be considered not only 

 on the basis of the commercial value of the forest resources, but on 

 that of the aesthetic and educational value of the virgin forest with its 

 typical examples of tree species. 



The loss of a section of the forest which forms the attractive fea- 

 ture in the landscape, or is the only remaining example of the origi- 



