DEVELOPING PROTECTION FOR MONTANA "S FORESTS 

 FROM PESTS, INSECTS AND DISEASE 



The presence of insects and disease in Montana's 

 forests is a never ending threat to destroy timber and 

 to reduce tree growth. Each year the State suffers 

 losses of timber resources from bark beetles, leaf 

 eating insects, tree and root rots, leaf diseases, and 

 parasitic mistletoes. Rodents, such as porcupines, mice 

 and rabbits destroy and deform many forest trees and 

 although they are not insects or diseases, are included 

 in the list of forest pests. 



Insects and disease are called the silent killers 

 of our forests. Daring the summer of 1967, parasitic 

 plants, like dwarf mistletoe, were active on 1,351,000 

 acres of Douglas -fir, 309,000 acres of lodgepole pine and 

 991^,000 acres of western larch stands in Montana. 

 Estimated growth losses caused by dwarf mistletoe during 

 the year 1967 in Montana are: Douglas-fir, 12,711^,000 

 cubic feet; lodgepole pine, 59,631,000 cubic feet; and 

 western larch, 12,1*89,000 cubic feet. 



Also in 1967 Montana lost an estimated 50,000 trees 

 in the Clark Fork and Flathead River drainages to a single 

 species of insect, the Ips bark beetle. This number of 



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