igQ MISC. PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 



ness of the terrain, the accessibility of the area, the current cost of 

 labor, and so many other factors that it is impossible to give any 

 specific costs which might apply to a given situation. Some idea 

 of the approximate cost of the work, however, may be obtained from 

 exj^erience gained daring the decade from 1921 to 1930. 



In the ponderosa pine region of California, Oregon, and Washing- 

 ton the control of the western pine beetle cost on an average about $4 

 per treated tree, with the cost in some cases dropping as low as $1.75 

 per tree. In the control of the Black Hills beetle in ponderosa pine 

 of the Rocky Mountain region the cost per tree averaged about $1.50 

 with some costs as low as 75 cents per tree. 



The control of the mountain pine beetle in lodgepole pine forests, 

 where either the solar-heat method or the fell-deck-burn method was 

 used, cost on the average from 50 cents to $1 per treated tree, de- 

 pending largely on the intensity of the infestation. Under similar 

 conditions the solar-heat method is the cheaper of the two. 



The control of mountain pine beetle infestations in western white 

 pine cost about $4.50 per tree, and in sugar pine, on account of its 

 very large size, the costs sometimes amounted to as much as $16 per 

 tree. 



For the treatment of a few scattered trees around summer homes 

 or in inaccessible areas the costs will run higher than on large-scale 

 projects. 



Bark-beetle control work has been in progress in western forests 

 since 1911, and the results of this work have indicated rather 

 definitely what can be expected in the control of some of the more 

 important species (27) . 



'Wherever bark beetles have been primarily responsible for the 

 death of trees, the application of control measures has resulted in 

 reducing tlie infestation or in restoring the natural balance so as 

 to bring the outbreak under control. With such aggressive tree- 

 killing species as the mountain pine beetle and the Black Hills beetle, 

 control work has been very effective in quickly suppressing outbreaks 

 wherever a high percentage of the infested territory could be covered 

 in a single season and the results were not nullified by migrations 

 from distant areas. Western pine beetle epidemics have so fre- 

 quently been partly dependent upon a weakened condition of the 

 host tree that the insults from control have not been so clear-cut. 

 Infestations have been reduced, but unless the work is continued 

 or conditions bring about improved tree resistance, the reductions 

 brought about by control efforts are difficult to maintain. 



At best, remedial bark-beetle control is only a temporary expedient, 

 or a method of suppressing outbreaks that have been brought about 

 through some interruption, disturbance, or failure of the biological 

 balance. The only permanent protection is through the management 

 of forest properties so as to maintain the natural balance, or if this 

 is broken by forces beyond man's control, to be able to salvage the 

 killed timber quickly enough to prevent excessive loss. 



