The Douglas-fir tussock moth (Orgyia pseudotsugata McDunnough) is an important defoliator of true firs and Douglas-fir in Western North America. Severe tussock moth outbreaks have occurred in British Columbia, Idaho, Washington, Oregon, Nevada, California, Arizona, and New Mexico.
Defoliation by the tussock moth kills or top-kills many trees, weakens additional trees that are eventually killed by bark beetles, and retards tree growth for several years. More information on biology of the moth is available at Forest Insect Disease Leaflet 86: Douglas-fir Tussock Moth.
TM Biocontrol-1 is a viral biopesticide produced by the U.S. Forest Service that is used, along with various commercial Bacillus thuringiensis products, for the control of the Douglas-fir tussock moth in the Pacific Northwest. For information on ongoing research to improving the efficacy of these products, go to Biopesticides for Control of Douglas-fir Tussock Moth.
For information on an Early Warning System with a pheromone-based trapping system to detect outbreaks, see Early warning system for Douglas-fir tussock moth outbreaks in the Western United States.
For synthesis of research and management findings and recommendations, see Douglas-fir tussock moth handbook: techniques for monitoring the effects of insecticides on forest fauna.