KUOW - Japanese - beetle pesticide spraying coming to south King County

kuow.org · Feb 26, 2026 · Collected from GDELT

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In a first for western Washington, agriculture officials are gearing up to spray insecticide to fight an infestation of Japanese beetles in south King County, near Seattle. The Washington State Department of Agriculture aims to spray up to 2,000 properties, covering about 1,000 acres of lawn in south King County, starting in late March.The juvenile beetle grubs live underground and are killed when they eat grass roots that have absorbed the pesticide.Bag traps in south King County caught 865 Japanese beetles in 2025, a major increase over previous years.“That is definitely indicative of an establishing population,” said Camilo Acosta, Japanese beetle eradication coordinator with the Washington State Department of Agriculture. Adult beetles can skeletonize the leaves of more than 300 species of plants, including farm crops, backyard vegetables, and ornamental plants.The spraying program is centered on the Angle Lake area, just south of Sea-Tac Airport. Spraying is also planned for smaller areas scattered through Burien, Des Moines, Normandy Park, Kent, and Renton, and Tukwila where the beetles have been found. The “reduced-risk insecticide,” known as Acelepryn, with the active ingredient chlorantraniliprole, can only be sprayed where property owners give permission.The agriculture department sent letters to affected property owners in January, seeking permission to spray on their properties. The U.S. Environmental Protection Agency registered chlorantraniliprole as a reduced-risk pesticide, safer for humans and the environment than alternative chemicals used for the same purpose, in 2008.“Acelepryn has a very good safety record when you use it according to its label,” Acosta said.Acelepryn is “not a risk to mammals, birds, or fish when used according to label instructions,” according to the Washington Department of Health. The agency says the pesticide can harm aquatic invertebrates and should not be used near bodies of water.The agriculture department has been attempting to eradicate the shiny green invaders in the central Washington cities of Grandview, Pasco, and Wapato, with mixed results. Beetle traps bagged 69,000 Japanese beetles in Yakima County and 2,400 in Franklin County in 2025.Acosta said about 40% of property owners in the target areas in central Washington have agreed to have their lawns sprayed. “Japanese beetles, they don't see borders, they don't see boundaries, so they're just going to fly over and reinfest these other yards,” Acosta said. “So it is very important that we get as close to 100% consent levels as possible.” How or when the plant-chomping invaders arrived in King County is uncertain, but Acosta said it is likely they hitchhiked to Sea-Tac Airport, rather than spreading from their populations on the other side of the Cascades.“Japanese beetles actually really like to ride airplanes for some reason,” he said.“The Port has been diligent about treating the areas around the airport since 2014 but this year there’s been a much larger population detected off airport property just a short distance away,” Port of Seattle spokesperson Perry Cooper said by email. Cooper said just seven to 12 Japanese beetles were captured on airport property in 2025, while a single trap at Angle Lake captured 142 of the unwanted insects.Conservationists said they recognize that the Japanese beetle is a worrisome pest, but expressed concern about the impacts of spraying a long-lasting pesticide on beneficial insects like butterflies and bumblebees.Chlorantraniliprole kills butterflies and moths, even at low amounts, according to Aaron Anderson, pesticide specialist with the Xerces Society for Invertebrate Conservation in Portland.“Whether the benefits of trying to control the beetle in a dense urban area are worth the potential non-target effects is hard to assess,” Anderson said by email. “Often, when it comes to an invasive [species], the early detection and rapid response approach does avoid more extensive long-term use of pesticides.”After spraying beetle-infested areas in Portland and Beaverton for three years, the Oregon Department of Agriculture discontinued its Japanese beetle program in late 2025. Oregon officials sprayed 4,000 properties covering 950 acres in 2025 and trapped 1,900 beetles, down from 23,000 beetles in 2017. The Oregon Association of Nurseries has been lobbying the state to resume the program and help nurseries save their out-of-state sales from a potential quarantine aimed at preventing the spread of the beetles to other western states. If you find a Japanese beetle and want to kill it without pesticide, you can drop it in a bowl of soapy water. The Japanese beetle is bright, iridescent green and bronze, unlike native beetles in western Washington. The shiny green beetles were first found in the United States, in New Jersey, in 1916. Since then, they have infested most of the eastern United States, where they're considered a highly destructive pest.