Insect identification > Coleoptera > True Coleoptera > Japanese beetle

Japanese beetle

The Japanese beetle (Popillia japonica Newm.), a native of Japan, was discovered in New Jersey in 1916. The beetles attack the foliage and fruit of many kinds of plants, including fruit trees, small fruits, garden crops and ornamental trees and shrubs; the larvae feed on the roots of grasses and other plants.

Since 1916 this insect has become extremely abundant in New Jersey and in the nearby sections of the adjoining states where it is a serious pest. It has also been captured as far North as Maine, New Hampshire, Vermont, western New York and Pennsylvania, Ohio, Michigan (Detroit), and southward in West Virginia, Virginia and North and South Carolina and will probably spread much farther.

The adults are about 0.5 inch long, the head and thorax bronze-green; the elytra brownish; there are two white spots at the tip of the abdomen. They begin to appear in June but are most abundant in July and August; lay their 40 to 50 eggs in the ground and the grubs, on hatching, feed on decaying vegetation and living plant roots but on the approach of cold weather go more deeply into the ground. Here they stay until April when they come up and resume feeding until pupation in June, followed by the emergence of the adults, there being one generation a year.

Many other scarabaeids are occasionally injuriously abundant in different parts of the country but can hardly be considered as of nationwide importance. The largest beetles found in the United States also belong here and are called rhinoceros beetles. One species, Dynastes tityrus L., about two and one-half inches long, is greenish gray with black spots on the elytra. The male has a long horn on the head, projecting forward and upward, and another projecting forward from the pronotum. The female has only a small tubercle on the head.

It occurs in the Southern states. In another species found in the West the prothoracic horn is much longer.