Popillia japonica
Pest description and crop damage This invasive pest is present in isolated populations in Portland and Beaverton areas and may soon spread to hazelnut orchards because eradication efforts are no longer being funded in OR. This small scarab beetle has copper-colored elytra (wing covers) and a green head and thorax. Small white tufts of hair project from the sides of the abdomen. The adult is a little over 0.5 inch in length. The grubs are "C" shaped, are 1 inch long when mature, and are found on grass roots in the soil. Hazelnuts are a favorite host plant for the adult beetles and large aggregations of adult beetles can skeletonize/defoliate whole trees.
Biology and life history Eggs are laid near the soil surface and grubs feed below on fine roots and other debris. The lifecycle is completed within one year.
Management
This pest has not yet been documented attacking commercial hazelnut orchards, but it is beneficial to be aware of the threat. If you see Japanese beetles in a commercial orchard situation, please report it to OSU Extension.