Oriental Beetle (Exomala orientalis) — identification, habitat & look-alikes

The oriental beetle is a small scarab from East Asia whose white grubs are a serious turf pest in lawns and golf courses of the eastern United States. Adults are about 0.3–0.5 in (8–13.5 mm) long and range from pale tan to nearly black, usually with mottled markings.

Appearance

Appearance: A rounded beetle about 0.3–0.5 in (8–13.5 mm) long. Wing covers are usually mottled brown and black, but color varies from almost unmarked light tan to solid black.

Look-alikes

Japanese beetlePopillia japonica

Adult Japanese beetles are larger and much more colorful than the dull, mottled oriental beetle. The grubs look the same, but with a hand lens the spines under the tail tip form a V in Japanese beetle grubs and two parallel rows in oriental beetle grubs.

Why they get mixed upBoth are Asian scarabs that appear in early summer, and their grubs damage the same lawns.

Where it lives

Typical habitats: lawns
golf courses
nurseries
flower gardens
Range: Native to East Asia, including Japan and Korea. It reached Hawaii by 1908 and was first found on the mainland in Connecticut in 1920. It has since spread to many eastern states, including New York, Maine, and North Carolina.
Preferred conditions: Grubs live in the top few inches of soil under turf and move down 8–17 in (20–43 cm) to spend the winter.
When to see it: In the US
Active Jun–Aug

Behavior

Diet: Adults visit flowers such as roses, hollyhocks, phlox, petunias, and dahlias but rarely cause real damage. Grubs eat turfgrass roots, especially Kentucky bluegrass, perennial ryegrass, and sheep fescue, and can also hurt nursery plants.
Activity: Adults are out from about mid-June to mid-August. Each adult lives only about two weeks, mainly to mate and lay eggs.
Overwintering: Overwinters as a grub deep in the soil. Most finish growing in one year, but some take two years, and both kinds can live in the same lawn.

Life cycle

Larva: A C-shaped white grub that is nearly identical to a Japanese beetle grub. Females lay eggs in the soil, and the grubs hatch in about two weeks.