State proposes springtime eradications to protect communities from invasive pests

Treatments planned for King, Pierce, Yakima, Benton and Franklin counties

OLYMPIA – The Washington State Department of Agriculture (WSDA) Pest Program is proposing eradication projects for the spring of 2026 to eradicate spongy moth and Japanese beetle. The eradication sites were proposed after the program completed analysis of 2025 trapping data and found evidence of reproducing populations of both invasive pests in the proposed treatment areas. 

 

Spongy moth: King and Pierce counties

The spongy moth eradication proposal includes treating two sites for spongy moth caterpillars, one site west of Lake Youngs in King County and one site in the Lakewood area of Pierce County. The WSDA Pest Program proposes to aerially treat 874 total acres with Bacillus thuringiensis kurstaki (Btk), a naturally occurring soil bacteria frequently used for caterpillar control in organic farms and gardens. Btk has an excellent safety record for humans, pets, birds, bees and fish.

Interested residents can visit WSDA’s 2026 spongy moth eradication webpage for interactive and printable maps, information about the proposed eradication and treatment notification signup. 

WSDA will conduct extensive outreach to impacted residents, including several mailings to residents in addition to other outreach before the treatment proposal is finalized. 

WSDA has successfully prevented spongy moth from establishing in Washington state for over 50 years by consistently monitoring moth introductions with traps and safely conducting eradications when necessary. 
 

Japanese beetle: Yakima, Benton, Franklin and King counties

The WSDA Pest Program continues its Japanese beetle eradication efforts this year, expanding the treatment areas to include more of Pasco and, for the first time in Western Washington, treatments in the SeaTac area. The program seeks to treat a total of 12,889 properties, of which 1,350 properties are in King County and the remainder are in Yakima, Benton and Franklin counties. Most treatment properties are in the Grandview area, where the Japanese beetle infestation was first detected. 

Japanese beetle treatments consist primarily of spring lawn treatments using Acelepryn, a reduced-risk insecticide approved for controlling beetles. The program may also conduct foliar treatments using the same product in the summer in high-catch areas, funding permitting. 

Residents in the proposed Japanese beetle treatment areas will receive a letter this month with more information. Additionally, anyone can visit WSDA’s Japanese beetle webpage to learn more and see if they are in a proposed treatment area.
 

Next steps

The WSDA Pest Program will conduct public outreach to impacted areas, complete environmental reviews, secure funding, and work with stakeholders before finalizing the proposed treatment areas. 

WSDA’s Pest Program is tasked with monitoring for invasive pests that threaten agriculture, forests and urban environments. It has decades of success eradicating numerous pests, including citrus longhorn beetle, northern giant hornet and dozens of introductions of spongy moth. This, in turn, has preserved the environment for Washington residents and tourists and prevented costly control and quarantine costs for the agriculture industry.