Wednesday, March 22, 2023
March 22, 2023

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Eastern Washington quarantine grows for destructive beetles


Washington has extended its quarantine to prevent the spread of an invasive beetle that destroys vegetation from roses to grape vines farther into western Benton County.

The quarantine area is within a couple miles of Prosser after an emergency expansion in December.

The Washington state Department of Agriculture had some success in 2022 in decreasing the number of Japanese beetles already in Eastern Washington, but they have continued to spread beyond where they have previously been detected.

The highly destructive beetles feed on more than 300 ornamental and agriculture plants, turning the plants into skeletons as they consume the foliage, flowers or fruit.

They also can attack grass roots, damaging lawns, golf courses and pastures, according to the U.S. Department of Agriculture.

“If Japanese beetles were to become established in Washington, it would pose a serious threat to gardens, parks and farms by destroying vegetation,” according to the state Department of Agriculture.

“Costly quarantines would also be established, making it increasingly difficult and expensive to move Washington agricultural products and even nursery plants within and outside of the state,” it said.

The Oregon Department of Agriculture estimated that if Japanese beetles were to establish there, the economic impact to their crops, commodities and other related businesses could be approximately $45.5 million.

In 2020, Washington State Department of Agriculture detected two Japanese beetles near Grandview and one near Sunnyside. In addition, a Grandview resident reported that she had numerous Japanese beetles devouring her roses that summer.

In 2021, the state Department of Agriculture trapped more than 24,000 beetles in and near Grandview, including across the Yakima County line into Benton County.

Tri-Cities Japanese beetle

Last year, the number of beetles trapped dropped to about 23,000, although officials were surprised when the first one was found in the Tri-Cities in Richland. It was discovered near Truman Avenue, near the Richland Target.

In response, state officials set up 49 traps in the square mile surrounding the area where the Japanese beetle was found. None of the traps caught a Japanese beetle, leading state officials to conclude it was a single bug that had not bred.

There is a nursery nearby and that may be how the beetle was brought into the area.

The beetles are native to Japan and their larvae hide under the soil and can be spread by moving potted plants, compost, grass clippings and soil fill.

Adults can be moved many miles on airplanes, trucks and trains.

So far the Japanese beetles have found along about 65 miles the Washington Interstate 82 corridor, a major pathway for much of the state’s agricultural production, according to the state. Most have been found in the Grandview and Wapato areas.

The quarantine area in the Grandview area in both Yakima and Benton counties prohibits movement outside of the area of items known to transport beetles. They include cut flowers, bulbs, potted plants, yard and vegetable garden debris, and topsoil.

Those within the quarantine area must take their yard debris to a drop-off yard at 874 Bridgeview Road in Grandview from May to October.

The Department of Agriculture also is fighting the Japanese beetle infestation with treatment of turf grass in the Grandview area, including at homes and parks, with insecticide that kills larvae in the ground.

Those with property that the state would like to treat this spring for free should be getting a letter asking for permission in January or February.

The state also is putting out more traps. That slightly fewer Japanese beetles were caught in 2022 than the year before, despite more traps set, is encouraging, said Amber Betts of the Department of Agriculture.

The beetles emerge — usually from lawns or other soil — in the spring. They feed on plants in the summer and then larvae over winter in the soil.

What Tri-Citians can do

Usually adult beetles are spotted in Central and Eastern Washington starting in June and may be seen into October.

The adult beetles are metallic green and brown and have little tufts of white hair on their sides.

Residents of Benton, Franklin and Yakima counties are asked to report any Japanese beetles they find.

They can be reported at or by email to with contact information, the location, date, photographs of the beetles and the number seen.

Or they can call 800-443-6684.

Residents also can help by purchasing traps sold at home and garden stores and using then on their property from spring through fall, according to the state.

The traps allow any beetles caught to be killed and help the state track the infestation.