The Western Spruce Budworm is a widespread destructive Nearctic moth species in western North America that feeds on coniferous trees. It is found in :the Rocky Mountains from Arizona and New Mexico northward into Colorado, Utah, Wyoming, Montana, and Idaho; in the Pacific Northwest in Oregon and Washington; and in British Columbia and Alberta, Canada" (US Department of Agriculture Forest Service 1992
"The first recorded western spruce budworm outbreak was in 1909 on the southeastern part of Vancouver Island in British Columbia, Canada. Since that year, infestations of this and related species frequently have been reported in western Canada" (US Department of Agriculture Forest Service 1992).
Host tree species include: Douglas-fir (Pseudotsuga menziesi), grand fir (Abies grandis), subalpine fir (Abies lasiocarpa), Engelmann spruce (Picea engelmannii), white spruce (Picea glauca), and western larch (Larix occidentalis)