JAPANESE BEETLE (JB): Popillia japonica Newman Order - Coleoptera: Family - Scarabaeidae

DISTRIBUTION: Imported into New Jersey from Japan about 1916, the Japanese Beetle has spread (2003) to all states east of the Mississippi except FL, and portions of MN, IA, MO, AR, and OK. It is being eradicated in NE, KS, TX, and CA

DESCRIPTION: Small white eggs (Fig 2) are found in the soil. The larvae (Fig 3) are small (up to 1”), creamy white grubs. The posterior plate (rastor) is gray. Hair on the rastor forms a distinct “V” shape distinguishing it from other “white grubs.” When found in the soil, the larvae are usually curled into a “C” shape. Whitish pupae (Fig 4) are found in soil.

The adult beetle (Fig 1) is oval and about ½” in length. The head and thorax are bright metallic green, the wing covers are brown, and there are white spots on each side of the abdomen.

HOSTS: Together the adults and larvae feed on more than 300 species of plants. Ornamental trees, shrubs and sod make up the largest portion of host plants. Corn silks, a few weeds and wild grapes are also favored.

DAMAGE: Adults feed on both foliage and blooms. Seen from a distance, heavily infested plants appear scorched. The adults remove leaf tissue between veins so that the leaves look like brown lace.

Larvae feed on fibrous roots of grasses and occasionally roots of adult hosts. Sod turns brown and dies as larval populations increase. Heavily infested sod can be pulled back like a carpet to reveal the “C” shaped larvae beneath and lack of fibrous roots.

INSPECTION TIPS: Both adults and larvae are active during the warmest hrs of the day. Adult activity on smartweed and wild grape can be good indicators of JB population levels in adjacent areas. Moles may be present if earthworm or grub populations are high.

LIFE CYCLE: One-year life cycle. Adults lay 40-60 eggs in grassy areas from the end of June to beginning of August. Eggs hatch and larvae begin feeding on the roots until fall. As temperatures decrease larvae move deeper into the soil where they overwinter. As soil temperatures rise in spring the larvae move back to the root zone and feed until they pupate around the first of June. The pupal stage lasts approximately 2 weeks. When adults emerge they fly to host plants where they feed and mate. The female returns to the soil to lay eggs. Adults live 30-45 days.

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