Unprecedented Spruce Budworm Outbreak Spreads Across Washington
The Washington State Department of Natural Resources' annual Forest Health Highlights report found 391,000 acres of dead or damaged trees and invasive species outbreaks in Chelan, Kittitas, and Okanogan counties.
What the 2025 Forest Health Report Found
The report found an outbreak of western spruce budworm remained active and visible along State Route 20, impacting 150,000 acres from the Mt. Baker area in Whatcom County east to Chelan and Okanogan Counties. Officials note the size of the outbreak is not uncommon, but an outbreak reaching as far west as Whatcom County is unprecedented.
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“The area affected by western spruce budworm has more than doubled in the last two years,” DNR Forest Entomologist Glenn Kohler said. “The unusual activity so far west in the Mt. Baker area is persisting. Spring sampling indicates we’re likely in for another year of damage and potential spread to new areas in 2026.”
Spruce Budworm Outbreak Expands Westward
There is also a second cyclical outbreak on the horizon for eastern Washington. The average number of Douglas-fir tussock moths captured increased threefold in 2025 compared to 2024. Officials say this is a precursor that happens every seven to 10 years. The most recent outbreaks in 2018 and 2019 defoliated 7,500 acres in Chelan, Okanogan, and Kittitas counties following a period of unusually high trap counts.
Kittitas, Klickitat, Yakima, and Okanogan counties saw elevated trap catches in 2025. Larvae and egg masses were also observed in Klickitat and Lincoln counties.
Officials note that high trap-catch numbers do not always correlate with the exact location of future defoliation events.
Staffing Cuts Impact Forest Monitoring Efforts
Officials say that roughly 25% of the forested land across Washington was not surveyed for the first time since 2021. This is due to staffing cuts of the U.S. Forest Service.
“One of my biggest concerns with the restructuring of the Forest Service is how changes to the federal workforce could negatively impact critical programs in Washington state,” Commissioner of Public Lands Dave Upthegrove said. “We value our strong, positive relationship with the Forest Service and are in close contact with them. It is imperative that federal leadership restore the positions necessary to ensure the continued success of our joint aerial survey.”
DNR Taking Over Aerial Detection Survey
The Aerial Detection Survey will be taken over by the Department of Natural Resources and will rely more heavily on aerial surveys.