(Popillia japonica)
As their name suggests, these beetles are native to Japan. They were first seen in New Jersey in 1916 and have since become a major pest in the eastern United States. They feed on hundreds of different species of plants. The adult beetles are present from June to October. They feed only in the daytime, and are most active on warm, sunny days. The female beetles live for 30 to 40 days. Just before they die, they lay their eggs just under the soil surface in lawns. Grayish white grubs soon hatch and feed on grass roots. As the weather turns cold in the late fall, the grubs move 8 to 10 inches down into the soil, where they remain dormant for the winter. When the soil warms up in the spring, the grubs move back up near the soil surface and resume feeding on roots. They soon pupate and reemerge as adult Japanese beetles in late May or June.
Control the adults with an insecticide containing acephate, carbaryl, or malathion in late May or June. Make sure your plant is listed on the product label. Repeat the spray 10 days later if damage continues. For a list of plants rarely fed upon by adult Japanese beetles, see Plants Rarely Fed Upon by Adult Japanese Beetles.
