Two blends (Natural and Phillips) of the western pine shoot borer pheromone, formulated as Hercon Luretape, were applied to six ponderosa pine plantations in northern Idaho and western Montana in 1984. The treatment was approximately 21.6 grams of pheromone per hectare. Significant reductions in damage have occurred in all treated plantations. Damage has been reduced most in plantations that are not surrounded by pine stands which provide a reservoir of moths that can reinvade treated areas. The best results to date have been a reduction of infested terminals from 50.9 to 1.6 percent after 2 years of treatment. Population trends in nearby check areas were either static or increasing. Treatment effects of both the Natural and Phillips formulations were significantly different from the control at the 99 percent level. However, these treatments were not different from each other.