Japanese Beetle - Recognizing Life Stages Japanese Beetle - Recognizing Life Stages

The adult Japanese beetle is a little less than 1/2 inch long and has a shiny, metallic-green body and bronze-colored outer wings. The beetle has six small tufts of white hair along the sides and back of its body under the edges of its wings. The males usually are slightly smaller than the females. You are most likely to see the adults in late spring or early summer.

During the feeding period, females intermittently leave plants, burrow about 3 inches into the ground - usually into turf - and lay a few eggs. This cycle is repeated until the female lays 40 to 60 eggs.

By midsummer, the eggs hatch, and the young grubs begin to feed. Each grub is about an inch long when fully grown and lies in a curled position. In late autumn, the grubs burrow 4 to 8 inches into the soil and remain inactive all winter. This insect spends about 10 months of the year in the ground in the larval stage.

In early spring, the grubs return to the turf and continue to feed on roots until late spring, when they change into pupae. In about 2 weeks, the pupae become adult beetles and emerge from the ground. This life cycle takes a year.


Japanese Beetle Adult Japanese Beetle Larva


Japanese Beetle Eggs Japanese Beetle Pupae

Courtesy of the USDA.

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