The Extension Service is here to serve the residents of Columbia County, providing knowledge from universities nationwide. We provide research-based information to families, youths, schools, agricultural producers, home gardeners, foresters and governments.
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A significant population of Japanese beetles has been found in southwest Portland in the Cedar Mill area. Based on the numbers trapped, they appear to have been there awhile and grown into a breeding colony. This is not the first time they have been found in Oregon but it is the largest outbreak so far. Earlier population around the Portland airport and one near Tigard were quarantined and destroyed. So was a population in Cave Junction in Southern Oregon. The Oregon Department of Agriculture will be doing aggressive treatment and monitoring of the affected area in SW Portland this year and for several years more to assure the population is eradicated. But since is is a densely populated area and the adult beetles are strong fliers, it is going to be challenging.
Former east coast residents are probably familiar with Japanese beetles. They appeared in New Jersey in 1916 (perhaps in imported iris rhizomes from Japan) and have spread to most of the States east of the Mississippi. Some are now found west of the river and are slowly picking a path further west.
This insect has an alarmingly long list of plants it likes. The grubs are inordinately fond of grass roots. They have devastated lawns and pastures throughout the regions where they have established. Millions of dollars and tremendous amounts of insecticides are used to manage them. Adult Japanese beetles seem to have very few plants they don’t like. Beans, melons, and corn are popular as well as a long list of ornamental trees, shrubs, and herbaceous plants. Adult feeding skeletonizes the leaves.
So, what can we do now? The most important role we can play is to learn to identify the adult Japanese beetle. Fortunately, they are quite distinctive. Japanese beetle adults are slightly less than 1∕2 inch long, and are shiny, metallic green. They have coppery-brown wing covers that do not entirely cover the abdomen. There are six pairs of patches of white hairs along the sides and back of the body, under the edges of the wings. The only thing that might be confused with it is the golden buprestid which is similar in size and also metallic green but otherwise quite different in appearance.
If you find what you think is a Japanese beetle, capture it and take precise notes as to the location. Log on to www.oregoninvasiveshotline.org to report your find. If you can send a picture of the insect so much the better. Freeze your specimen until you have heard from someone. You can also bring it to me at the Extension office to look at.
Hours of Operation
8 a.m. to 5 p.m.
Closed Fridays from Noon to 1 p.m.
OSU Columbia County Extension
505 N. Columbia River Hwy
St. Helens, OR 97051
For information on public transportation, visit the Columbia County Rider website.
We offer classes, workshops, opportunities for youth and adult volunteer activities:
Nutrition education events
Home Garden educational events