Crops threatened after invasive Japanese beetle discovered in Pasco

A single Japanese beetle —  a highly invasive pest also known by its scientific name Popillia japonica — was discovered in Pasco last week, according to The Washington State Department of Agriculture (WSDA).

The beetle invades more than 300 local plants, including roses, grapes, and hops. Japanese adult beetles damage plants by skeletonizing the foliage. Experts with Washington State University (WSU) fear the beetle could make its way across the state within two decades if steps aren’t taken to stop them.

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A Franklin County Horticultural Pest and Disease Board trapper found the beetle, and state officials responded to the catch, verified the beetle, and set up a delimiting trapping grid around the find.

If a trap detects multiple beetles, the state’s response becomes a main priority as the potential for Japanese beetles to establish themselves in Washington becomes a significant concern, according to WSDA. The department revealed the Oregon Department of Agriculture estimated that if Japanese Beetle were to establish, the economic impact on their crops, commodities, and other related businesses could be approximately $45.5 million.

“This is an excellent example of just how important agency collaboration is,” Camilo Acosta, WSDA’s Japanese beetle eradication project coordinator, said in a prepared statement. “A single beetle is less cause for concern because one beetle can’t reproduce. But we need to be sure there are no more. Last year, a single beetle was found in Richland, but extensive trapping in the area did not detect additional beetles.”

The beetles can get into air cargo from the Eastern United States and transported to the West.

The Japanese beetle is metallic green and brown in color, with little tufts of white hair on their sides. The grubs — a general term for the larval stage of beetles — develop into adults while overwintering in the soil from fall to spring, coming out of lawns or other soil in summer when temperatures warm up.

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“Preventative pesticides for grubs need to be applied before adult beetles lay eggs in July and August,” WSU wrote in a handbook on dealing with Japanese beetles. “It kills eggs and helps control next year’s grub population. Labels often say ‘Season Long Control.'”

In 2020, WSDA detected two Japanese beetles near Grandview and one near Sunnyside. Over the next two years, WSDA trapped over 24,000 and 23,000 beetles within the same area. Beetles were also trapped in Wapato in 2022. This year, teams have caught approximately 6,600 beetles.

If you live in Washington and think you see a Japanese beetle, you’re asked to take a picture and report the sighting online, especially if you live in Yakima, Benton, or Franklin counties.