From Ohio History Central
It is safe to say that if you have roses in your yard, you have seen Japanese beetles (Popillia japonica). These metallic blue-green members of the scarab family of beetles are very destructive to garden plants and flowers. Besides their shiny coloring, they also have coppery, hard, leather-like wings.
It was introduced into the United States around 1916, on nursery plants from Asia. In its first eight years in the U.S., it spread 2,500 square miles. Since then, it has continued to spread slowly across the eastern United States, including Ohio, until it has reached the Mississippi River.
Eggs are laid in the soil under grass. The larvae that hatch ? sometimes up to 1,500 grubs in one square yard of sod ? feed on the roots of the grass and other plants on which adults feed. They over-winter deeper underground before coming out of the ground, as half-inch long adults, in mid-summer. Adults will live for approximately two months in habitats wherever their food is present. Japanese beetles may act alone or in swarms to attack a variety of garden plants as well as lawns, golf courses, shrubs and fruits. Using chewing mouth parts, adults typically feed on the leaves and flowers of a variety of plants, especially roses, but also grapes, berries, apples, corn, clover, soybeans, hollyhocks, elm and birch trees. They eat leaf tissues, between the veins, so a leaf that has been eaten by a Japanese beetle looks like lace.
There are a number of ways to control Japanese beetles. Naturally, they are prey for a number of parasitic wasps and flies. They are also susceptible to a bacterial disease known as milky disease, which attacks the larvae. Chemically, pesticides help to control the beetle but people should start early in the fall by spraying their soil in order to control the larvae before they emerge from the ground. Japanese beetle traps are a popular backyard method of control.