Larval instars were determined by entomologists. Oregon and Washington cooperative western spruce budworm control project.

Photo by: Unknown Date: 1976

Credit: USDA Forest Service, Region 6, State and Private Forestry, Forest Health Protection. Source: Region 6, Forest Health Protection historical files located at the Mt. Hood National Forest in Sandy, Oregon.

The following abstract is from the project report: 1976 Western spruce budworm control project Washington - Oregon. Forest Service, USDA. Pacific Northwest Region. <a href="https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev2_026568.pdf" rel="nofollow">www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev2_026568.pdf</a>

Abstract: A total of 365,702 acres infested with western spruce budworm was treated in Oregon and Washington during 1976. Of this total, 7,663 were treated with Sevin 4 Oil at the rate of 1 pound (AI) in 1/2 gallon of formulated material per acre, and 358,039 acres were treated with ultra low volume Malathion at the rate of 13 ounces of technical grade material per acre.

A total of 23 helicopters and 2 fixed-wing aircraft was used in applying the insecticide. In addition, 13 helicopters and 1 fixed-wing aircraft were used for observation and general administration of the project. A total of 1,558 flying hours occurred during the project with no accidents or injuries.

Environmental monitoring of fish, aquatic organisms, birds and bees revealed no adverse effects of the treatment with the exception of a temporary reduction in aquatic organisms in streams which were directly treated with insecticide. Where one-swath buffer zones were left along streams, no significant differences in aquatic insect drift was noted.