Japanese beetle outbreak in Washington Co.

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Japanese_beetleBy Oregon Dept. of Agriculture

A record number of invasive Japanese beetles have been detected in Washington County within the city of Portland this summer. To date, the Oregon Department of Agriculture has found 265 Japanese beetles in traps placed in the area as well as numerous live beetles causing feeding damage on roses and other plants. The evidence suggests a breeding population of the non-native insect has been established.

“What we know right now is that this infestation is localized yet producing enough adult beetles that we can find them feeding on roses and other plants in this area,” says Clint Burfitt, manager of ODA’s Insect Pest Prevention and Management Program. “Without community action, this pest will spread and cause an increased use of pesticides by homeowners and producers of agricultural crops such as cannabis, hops, nursery plants, and wine grapes.”

Additional traps have been placed in the vicinity of Northwest Saltzman and Northwest Thompson roads. It appears the infestation has been present for at least more than a year but not detected until this summer.

Japanese_beetleJapanese beetle is a major plant pest in other parts of the US. As a grub, it can be very destructive to turf. As an adult, the bright metallic green beetle with copper-colored wing covers will feast on a wide variety of plant material including trees, shrubs, flowers, fruits, and vegetables. It is a pest that can be destructive in urban and agricultural environments, and is also subject to agricultural quarantine regulations. ODA has been using an early detection, rapid response approach for years to find and eradicate populations of the pest. In the past, Japanese beetle has made its way into Oregon through air cargo carriers with multiple detections over the years near Portland International Airport. In recent years, ODA has conducted eradication projects in residential areas of Portland and Cave Junction.

No eradication plans have been made yet in response to the most recent outbreak. ODA will continue to trap for Japanese beetles in hopes of pinpointing the location of the breeding population and potential treatment next year.

“We encourage residents to cooperate with field technicians who are maintaining traps and to be aware that this infestation can be spread by the movement of plants, roots, and soil that originate from this area,” says Burfitt.