"The USDA Forest Service, USDI Bureau of Indian Affairs, and the Yakima Indian Nation Tribal Council carried out a project to suppress an outbreak of western spruce budworm on the Yakima Indian Reservation in central Washington. Thuricide 48LV, a biological insecticide using Bacillus thuringiensis variety kurstaki [Btk] as the active ingredient was applied undiluted at the rate of 1/3 gallon per acre to 70,827 acres. Application was made by helicopters and single engine airplanes. Early larval density prior to spraying averaged 27.3 budworm larvae per 45 CM mid-crown branch tip. Post-spray density averaged 1.0 budworms per branch for a 96.5 percent population reduction. Cost for the treatment was $15.35 per acre. ... Aero Tech provided 3 Air Tractor 400 airplanes and 2 UH1B-204 helicopters for application aircraft, 2 Bell 206s and 2 Hughes 500s for observation helicopters, and support personnel and equipment. One of the 204 helicopters was badly damaged in a crash and was replaced by a Bell 206 equipped for spraying. ... Aero Tech leased a privately owned airstrip and hanger at White Swan, Washington. All aerial activity was staged from this facility."