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By R. D. Erickson
The Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough) (Lepidoptera : Lymantriidae), is a destructive native defoliator of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, in semi-arid portions of southern British Columbia, including the dry, warm subzone of the interior Douglas-fir, ponderosa pine and bunchgrass biogeoclimatic zones. Specifically the IDFxh2, IDFxw, PPxh2, BGxh2 and BGxw classifications. Severe infestations occurred in 1916- 21, 1928-31, 1945-49, 1961-64, 1971- 76, 1981-84, and 1991-93, resulting in top-kill and extensive tree mortality.
For more information, see the Douglas - fir tussock moth Forest Pest Leaflet in the Canadian Forest Service bookstore.