The Japanese beetle infestation is growing exponentially in Washington as state officials work to keep the invasive species at bay.

On July 28, the Washington State Department of Agriculture confirmed a Japanese beetle catch found in Richland, more than 35 miles east of the current proposed quarantine zone in Grandview. Earlier this week officials confirmed a detection in Wapato, 30 miles west of Grandview, meaning detections have expanded over 65 miles of the I-82 corridor, a major pathway for much of the state’s agricultural production.

“Finding two detections so far from the original grid in two separate directions suggests the Japanese beetle population is spreading very quickly,” Camilo Acosta, Japanese beetle eradication project coordinator, said. “The longer the invasive pest continues to thrive here, the more difficult and expensive it will be to control.”

A WSDA pest program trapper was doing a routine check on Thursday afternoon in Richland, not expecting to find Japanese beetle so far from the current infestation. The trap produced a single beetle, and teams began immediately setting up additional traps and checking nearby nurseries for detections.   

State officials are urging growers and community members in Yakima, Benton, and Franklin counties to monitor for these beetles. Growers can consult crop protection specialists and community members can consult WSU extension’s website for guidance on protecting their crops and gardens from this invasive pest. WSDA mapping specialists created a real-time detection map that growers can use to determine how close they are to known Japanese beetle detections.

How far have the beetles spread?

WSDA is seeking the public’s help in determining exactly how far the infestation has spread. More than ever, public participation is key in fighting invasive species. With these detections so widespread along the I-82 corridor, WSDA is asking residents – especially in Yakima, Benton and Franklin counties – to look for and report Japanese beetles on their property.

If you live in Washington state and think you see a Japanese beetle, snap a photo and report the sighting online.

Identifying Japanese beetle

Japanese beetle adults are metallic green and brown and have little tufts of white hair on their sides. They emerge – usually from lawns or in other soil – in the spring and feed throughout the summer. From fall to spring the grubs (larvae) overwinter in the soil and slowly develop into mature adults ready to emerge again in the spring.

How can I help?

In helping rid the area of the pest, community members can help by trapping, reporting, and killing the insects on their properties. Residents that live in an area where the beetles have been detected can limit the spread by not moving plants that could harbor the beetles or soil from their property.

“We also urge you to leave your potted plants, or treat them with an appropriate insecticide, before moving outside of the area,” Acosta added.

Eradication plans

The next steps in the eradication effort include setting traps in and around the infestation area and any new detection sites and establishing a quarantine zone to prohibit the movement of items that could transport Japanese beetles into new areas.

A public hearing about the adoption of this proposed quarantine will be held Aug. 2 at 10 a.m. Residents can join at the Learning Center, 313 Division St., Grandview, or online. More information on the rule language or the rule-making process is available on the WSDA rule-making webpage. WSDA is also holding mid-season virtual open houses for residents on Aug. 4 at 6 p.m. and a virtual meeting for area growers on Aug. 9 at noon. Links to both meetings can be found on the WSDA Japanese beetle website.

After the summer flight season, WSDA will determine if emergency rulemaking may be necessary to expand that proposed quarantine to include additional areas of infestation.

History

In 2020, WSDA first discovered just three Japanese beetles in the Grandview area. Last year the department trapped more than 24,000 beetles. So far this year, teams have caught around 8,300 beetles. Japanese beetles are highly invasive pests of more than 300 plants, including roses, grapes, and hops. The adult beetles damage plants by skeletonizing the foliage. Adults also feed on buds, flowers, and fruit on the plants and are frequently intercepted with air cargo from the Eastern U.S.

Source: Washington State Department of Agriculture, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.