29 



broods may be killed; but the uncertain benefit to be obtained by this burning 

 is usually more than counterbalanced by the certain injury to healthy timber 

 and reproduction. The control of bark-beetle outbreaks in green standing 

 timber by fire should be undertaken only with the greatest caution and under 

 expert advice. In our opinion this method of control would usually do infinitely 

 more harm than good. 



After the beetles have killed a large part of the timber, fires are able to 

 obtain terrific headway in the masses of dead trees, and therefore to cause an 

 unusual amount of damage. There are at present large areas in southern 

 British Columbia where for miles all or nearly all the pines have been killed by 

 bark-beetles. The trees have been dead from one to ten or twelve years. When 

 fires occur in such material as this, often on a thin and rocky soil, the heat may 

 burn through to the rock and reduce the section to a timberless waste for gener- 

 ations. It is not at all improbable that the large areas of rock and range land 

 in southern British Columbia have been produced in past ages through this 

 joint action of beetles and fire. Whatever has happened in the past, it is prac- 

 tically certain that fires will eventually ruin the extensive areas now existing 

 in that region upon which the pine has already been largely or entirely killed, 

 as well as upon that in which the beetles are still actively operating. 



Fig 5. — Ips integer Eichh., autenna. Original. 



