Monday, March 6, 2017

This pest loves your flowers

Karla Salp
WSDA Pest Program Outreach Coordinator

What is green, shiny, and a pest that WSDA hopes doesn’t cross the river?

The Japanese Beetle

Japanese beetle is a metallic green and bronze beetle first found in the US in 1916. A beautiful bug to look at, those in the Eastern States and Midwest are familiar with the havoc this particular pest can inflict on the environment.

Smelling the Roses

Roses are one of the favorite plants that Japanese beetles attack. In fact, the scent used to attract the pests to traps has a very pleasant, floral scent. But roses aren’t the only plants the beetles attack. They eat the foliage, flowers, and fruit of over 300 different plant species, including favorites like grapes, hops, and cannabis in addition to roses.

How’s the lawn?

M.G. Klein, USDA Ag Research Service,

One sign that Japanese beetles (or their relative, the European chaffer) are in your area is to take a look at your lawn from late fall to early spring. Japanese beetles overwinter as grubs in the ground with lawns as a favorite location. They feed on the roots of your grass all winter long.

But that’s not the only damage they do. These grubs attract everything from raccoons to ravens. They dig up your lawn looking for a mid-winter tasty snack. The upside is one small natural control for Japanese beetles. The downside is that it destroys the turf and, sadly, even this predator feeding does not keep the beetles in check.

Monitoring for Japanese Beetles
Japanese beetles in trap

Both Washington and Oregon routinely monitor for this invasive bug, and last year Oregon found an infestation in Portland. Almost 400 beetles were found – the most ever in the state. Now the Oregon Department of Agriculture is poised to start a multi-year effort to eradicate the pest.

With the increased finds in Oregon, Washington is on alert for the potential for the bugs to cross the Columbia River into Vancouver. While WSDA normally has a few traps in the Vancouver, in 2017 a full-time trapper will be dedicated to placing about 400 traps in the area.

Don’t give pests a ride

Kevin D. Arvin,
While it’s unlikely that a beetle would actually fly across the river, the reality is that thousands of people cross the river from Portland to Vancouver every day. Whether a Washingtonian just drives back from working in the City of Roses or visits an Oregon nursery to find a favorite plant, the threat is real that humans could transport this pest beyond their natural flight capability.

Report suspected beetles
WSDA monitors for Japanese beetles throughout the state each year. However, if you think you have found Japanese beetle in your yard, take a picture and capture the bug if you can. Then be sure to contact the WSDA pest program at or call 1-800-664-6684.

Your roses will thank you and so will we.

Life cycle of the Japanese beetle
Unless otherwise noted, images in this blog are courtesy of the Oregon Department of Agriculture.