Japanese Beetle
Popillia japonica

The Japanese beetle is a serious pest of turf and ornamental plants. Grubs feed on the roots of turfgrass and adults feed on the foliage of more than 300 plant species.

Identification:

The Japanese beetle (Popillia japonica) is a beetle about 1.5 cm (0.6 inches) long and 1 cm (0.4 inches) wide (smaller in Canada), with shiny copper-colored elytra and a shiny green top of the thorax and head.

Injury:

From early July through September, the adults, with metallic green bodies (a), can be found on leaves, sometimes several per leaf (b). Young tender leaves are preferred and may be completely skeletonized by adults (c). The C-shaped larvae (grubs) can seriously damage grass roots and can be found under dead patches of lawn.

Biology and History:

There is one generation per year. Most of the year is spent as larvae in the soil. Larvae overwinter in earthen cells 4-12 inches below the surface. From early spring until June, they continue to feed on roots. Then the insects pupate near the soil surface. Adults fly in the daytime and are active on sunny, warm days over 6-12 weeks, beginning the first week of July. Eggs are laid in the soil, and larvae feed on roots into the fall.