The larch casebearer Coleophora laricella (Hbn.) is now established throughout all western larch stands in Region 1. Population levels have begun to fluctuate in some of the older infested stands; however, it is still on the increase in more recently invaded territory. During the past 2 years work was begun...
Numerous stands of western larch, Larix occidentalis, on the St. Joe, Coeur d'Alene, and Kaniksu National Forests, Idaho, show signs of gradual deterioration following repeated defoliation by larch casebearer, Coleophora Zaricella Hbn. (Tunnock et al. 1969). Stand deterioration can occur after 4 years of continued heavy defoliation. The main symptom...
The Douglas-fir tussock moth, Orgyia pseudotsugata McD., periodically
defoliates Douglas-fir, true firs, and other host trees in forests of
the western United States. In the Northern Region, these infestations
occur about once every decade.
This history covers the earliest recorded outbreak in northeastern
Washington from 1928 to 1930 and includes...
Dwarf mistletoes exert an impact on forest productivity, but this impact can be reduced through management practices. Even infested stands can yield considerable volumes if proper control methods are used. Projections of future yield increases due to control efforts are made. Cost of treatment in fiscal year 1973 was $51...
Epidemic populations of the western spruce budworm persist in the Northern Region. Aerial surveys made in August 1976 showed a decline in the acreage of aerially visible defoliation. In northern Idaho, the defoliated area dropped from 831,487 acres in 1975 to 655,711 acres in 1976, down 21 percent. Surveys in...
Mountain pine beetle populations began increasing in Glacier National Park in 1970. Numbers of infested trees increased steadily from an average of 12 to 115 per hectare from 1972 to 1976. Total hectares of infestation have increased from 445 in 1972 to 40,419 ha in 1976. Predictive equations estimate a...