Upon discovering Japanese beetles in the Grandview area two summers ago, state officials said the invasive species had the potential to spread to adjacent areas quickly.
Those fears were realized this week as Washington State Department of Agriculture officials confirmed Japanese beetles had been found in Wapato, almost 30 miles from the infested area in Grandview.
“While we have been detecting some beetles outside the proposed Japanese beetle quarantine area around Grandview, finding one so far from the main infestation indicates the beetles are spreading quickly — possibly through human movement of the pest,” said Camilo Acosta, the WSDA Japanese beetle eradication coordinator.
After hearing about the insects on local television and radio, a concerned citizen in Wapato contacted the WSDA Pest Program on Monday after capturing three suspected Japanese beetles in his garden. The pest was eating peas and grapes.
WSDA crews responded, found evidence of beetle damage to several plants, and collected and confirmed the Japanese beetle specimens from the homeowner, Acosta reported.
Officials urge growers in Yakima and Benton counties to monitor for the beetles and consult crop protection specialists or WSU extension for guidance on protecting their crops from this invasive pest.
Valley problem began in 2020
First found in New Jersey in 1916, Japanese beetles will eat more than 300 types of plants, including roses, grapes and hops. The adult beetles damage plants by skeletonizing the leaves. Adults also feed on buds, flowers and fruit on the plants and are frequently intercepted on fruit transported from the eastern U.S.
A Grandview resident first noticed the beetles on her roses in 2020. That prompted WSDA to deploy 1,900 traps across the state in 2021 to gauge the extent of the problem.
About 900 traps were set in a 49-square-mile area around Grandview, and these traps caught 24,048 beetles, Acosta said. Almost all of the beetles found in Washington were concentrated in this mostly residential area, prompting WSDA officials to begin their eradication plan this year.
The Japanese beetle larvae are found in soil associated with the roots of host plants. They are common under turf and sod, and can be moved in potted plants, WSDA media relations coordinator Amber Betts said. She noted beetles can lay 60-100 eggs, meaning there will likely be much more than 24,000 beetles in southeast Yakima County this year.
Grubs were found for the first time this year on June 13 in Grandview, and plenty of adult insects followed. So far this year, teams have caught around 8,300 beetles, Betts reported.
Eradication underway
In May, the Senske lawn care service company began spraying an insecticide to kill the beetles’ larvae in a 3,100-acre area centered around Grandview, Acosta said. He estimated there were 4,200 properties within the treatment area.
WSDA mapping specialists created a real-time detection map that growers can use to determine if they are within a mile of a known WSDA Japanese beetle detection.
“Last year we established a baseline by determining where the beetles were through extensive trapping. The first step to eradication was completed earlier this year by treating lawns — where the grubs develop — with insecticide in the infestation area in and around Grandview,” Acosta said. “This is the first step in what will be a multi-year process.”
Although applied this spring, the treatments only impact next year’s beetle population, he noted.
Last week, the WSDA opened a Japanese Beetle Response yard waste dropoff site at 875 Bridgeview Road in Grandview. Residents living in the infestation area in and around Grandview are asked to bring their yard waste there. The site is open from 7:30 a.m. to 3 p.m. weekdays, and there is no charge for disposal, the WSDA announced Friday.
To enter the gated yard waste drop-off area, residents must show ID and proof of residence in the infestation zone. Accepted documentation includes utility or water bills that match the ID or driver’s license.
Items accepted for drop off include brush, branches and roots; leaves; grass clippings; fruit and vegetable trimmings; weeds; flowers; plants; shrubs; sod; stumps if roots are attached; and topsoil containing vegetative material.
Public hearing is Tuesday
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 is planned at 10 a.m. Tuesday 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.
With thousands of beetles already seen in Grandview, and new evidence of the pests in Wapato, the WSDA is hosting a virtual open house at 6 p.m. Thursday, Aug. 4. Community members can join to learn more about the situation and ask questions, Betts said. Residents will hear from state experts and learn about the plans to attempt to eradicate the pest.
The WSDA is asking residents — especially in Yakima and Benton counties — to look for and report Japanese beetles on their property, Betts said. Anyone living in Washington who thinks they have seen a Japanese beetle is asked to snap a photo and report the sighting online.
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.
People are encouraged to trap beetles, and anyone can do it.
“Trapping will catch adult beetles, which can lower their population and is another way to limit the spread of this pest,” Acosta added.
A wide variety of traps are available for purchase online, or at local home and garden stores. Traps vary in design, so follow the instructions provided. Traps should be placed from mid-May through mid-October, when adult beetles are active.
Adult beetles are safe to touch as they do not sting or bite. They can be picked off vegetation and dropped into a bowl of soapy water to kill them. It is best to do this in the morning or evenings when beetles are less active.
“If you capture any beetles, please report them,” Acosta said. “We’re trying to count every beetle.”
Visit agr.wa.gov/beetles to learn more about this pest, ways to control or get rid of it, and to see WSDA plans for eradication.
