Japanese beetles are an active and growing threat in Washington State, with infestations concentrated in the Yakima Valley and expanding into new areas. In 2025, state trappers captured over 72,600 beetles, nearly triple the number caught in 2024. The state has established quarantine zones and is running an eradication campaign, but the pest is spreading faster than control efforts can contain it.
Where Japanese Beetles Have Been Found
The heaviest infestations are in the lower Yakima Valley. In 2025, the communities of Grandview, Sunnyside, Outlook, Mabton, and Prosser accounted for 68,237 of the beetles trapped statewide, up from 24,754 the year before. Nearby Wapato saw a slight decrease, dropping from 1,546 catches in 2024 to 1,117 in 2025.
The Tri-Cities area is seeing rapid growth. Beetle numbers jumped from 410 in 2024 to 2,407 in 2025, with most caught in Pasco and a small number (10) in Kennewick. On the western side of the state, a residential pocket in the city of SeaTac went from 32 beetles found in 2024 to 865 in 2025 after the state expanded trapping there.
Why Washington Takes This Pest Seriously
Japanese beetles feed on more than 300 plant species. Adults chew leaves down to a lace-like skeleton and also damage buds, flowers, and fruit. Grapes, apples, hops, roses, and turf grass are all targets. The larvae, white C-shaped grubs that live underground, feed on grass roots and the roots of nearby host plants. Left unchecked, a large population can devastate both agricultural crops and residential landscaping. For a state that produces significant quantities of apples, hops, and wine grapes, an established Japanese beetle population would be an economic disaster.
The Quarantine Zone
The Washington State Department of Agriculture (WSDA) maintains an emergency quarantine covering parts of Yakima and Benton counties, most recently expanded in April 2026. The quarantine restricts the movement of materials that could carry beetles or grubs out of the affected area.
Items that can never leave the quarantine zone include soil, sod, and hop bines and cones. Between May 15 and October 15, when adult beetles are active, the restricted list expands to include plants with soil attached (nursery stock, potted plants, fruit trees, mint roots), all plant cuttings and yard waste (branches, grass clippings, weeds), and unshucked corn ears.
Some items are never restricted: cut flowers, dormant plants and bulbs free from soil, and harvested produce like cherries, apples, grapes, baled hay, and dried mint, as long as no beetles are present. If you live in the quarantine area, yard waste should go to a designated yard debris drop-off rather than being hauled outside the zone.
Businesses that need to move regulated items out of the quarantine area must prove those items are beetle-free before transport. This typically means either working with WSDA to place and monitor traps on the property from May through October, or applying an approved treatment and keeping records. Anyone driving through affected areas should inspect vehicles for hitchhiking beetles and tarp open loads.
What the State Is Doing
WSDA uses an integrated approach: thousands of baited traps to monitor population size and spread, public outreach to help residents identify and report beetles, quarantine enforcement, and targeted insecticide treatments. The primary product used is a liquid insecticide called Acelepryn, which is sprayed on turf, ornamental shrubs, and trees in and around residential, commercial, and institutional properties. A granular version may be applied to soil in limited situations. Both forms kill adult beetles and larvae on contact or when ingested.
One significant challenge is getting permission to treat. WSDA needs property owner consent before applying insecticide, and cooperation has been declining. In 2024, only 44 percent of property owners in treatment areas agreed. In 2025, that number dropped to 38 percent. Untreated properties act as refuges where grubs survive and repopulate treated areas the following year, which helps explain why beetle numbers keep climbing despite ongoing efforts.
How to Identify Japanese Beetles
Adult Japanese beetles are about half an inch long with a metallic green head and thorax and copper-brown wing covers. The most distinctive feature is a row of five small white tufts of hair along each side of the abdomen and two more at the tip. Many beetles in Washington look superficially similar, so those white tufts are the key detail to check. The grubs are harder to identify on your own since several species of white grubs look nearly identical. WSDA typically needs a physical specimen to confirm a grub identification.
How to Report a Sighting
If you spot what you think is a Japanese beetle anywhere in Washington, report it to WSDA. Online or email reports get the fastest response. You can submit through the Japanese Beetle Watch form on WSDA’s website, email Pest@agr.wa.gov, or call 1-800-443-6684. Include your name and contact information, the location, the date, the number of specimens you saw, and a photo if possible. A clear photo showing the beetle’s back and side tufts helps WSDA confirm the identification without needing to send someone to collect a specimen.
What Residents in Affected Areas Can Do
If you live in or near the quarantine zone, the most impactful step is consenting to treatment if WSDA contacts you. The low participation rate is one of the biggest barriers to eradication, and each untreated property undermines the work done on neighboring lots.
Beyond that, inspect your yard for signs of beetle damage during the summer months. Skeletonized leaves on roses, grapevines, or fruit trees are a telltale sign. Brown patches of lawn that peel up easily, like loose carpet, suggest grub damage to grass roots underneath. Report any beetles you find, follow quarantine rules when moving plants or soil, and take yard waste to approved drop-off locations rather than composting or hauling it yourself. If you’re buying plants or soil from within the quarantine area, confirm with the seller that the material has been cleared for transport.