Japanese Beetle Infestation Not Slowing in Col. Basin, Yak Valley

The WA State Department of Agriculture says in their year-end reports the battle against the voracious Japanese Beetle is far from over.

  The beetle is spreading rapidly in the basin

WSDA says three times more beetles were trapped in the Outlook, Grandview, Sunnyside and other valley areas this year as opposed to 2024.  Numbers of beetles found in the Mid Columbia are also increasing.

That explains in part why we've seen more of those yellow 'bag' traps hanging on fences, telephone poles and other areas in the Tri-Cities.

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WSDA also says despite the treatments being free of charge, only 44 percent of affected landowners have given permission for the non-lethal chemical applications.

Last year, at least 17,000 affected parcels of land were identified as potentially having various amounts of the insects in SE WA.

The number trapped in Pasco went from 410 in 2024, to 2,407 in 2025.  The insects are monstrous eaters, they can eat, strip and kill over 300 plant, flower, and garden varieties, and are even known to attack commercial grapes, apples, and hops.

Because they strip the foliage when they eat, they end up destroying the plant. They are also known to eat and weaken new grass, such as sod that's not had a chance to put down deep roots.

The beetles, native to Asia, first arrived in the US in New Jersey in 1916, on bulbs and dirt from Japan. By 1932 they'd reached St. Louis, and they were first detected in WA three years ago when they showed up in Grandview.