Fighting the invasion of the Japanese beetle

By: Nancy Olsen - Extension agent

Are your plants being eaten from leaf to flower? Is your garden being invaded by metallic green and copper beetles? If the answer to each of these questions is yes, then you most likely have Japanese beetles.

Japanese beetles are about one-half inch long, with a shiny, metallic green with coppery brown wings. Grubs are white, slightly curled and have yellow brown heads. Grubs are about 1 inch long when mature.

First reported in North America in 1916, Japanese beetle grubs are serious pests of the roots of grasses and shrubs. The beetles feed on over 275 different kinds of shade and fruit trees, shrubs, flowers, small fruits, garden crops, and weeds. Areas of dead grass appear when large numbers of grubs burrow through the soil consuming roots. The larvae are especially noticeable during dry spells in September or early October.

The grubs overwinter in the soil, in spring they move to ground level, where they feed ravenously and pupate. Adults emerge as early as mid May in Eastern North Carolina. Peak emergence occurs in July. Throughout summer, the beetles attack the fruit and foliage of many plants leaving only a lacy network of leaf veins. Soon after emerging, females deposit 40 to 60 eggs in small batches 2 to 3 inches deep especially in damp soil. In warm, wet summers, eggs hatch in about two weeks. The newly emerged larvae feed until cold weather forces them into hibernation. One generation occurs each year.

Soil insecticides may be used in late August and September to control grubs feeding near the soil surface. Fall larvae control is more effective than Spring larvae control, due to the fact that the larvae is much smaller in the fall. Spring larvae have been feeding all winter and are a much larger grub and would be harder to control chemically. The residual life of the soil applied chemicals is relatively short, necessitating repeated applications each season. Diazinon, chlorpyrifos (Dursban), carbaryl (Sevin) and Milky Spore Disease are labeled for white grub control in turf.

Flowers and ornamental plants can be protected by dusting or spraying with some of the following pesticides: carbaryl (Sevin), malathion, imidacloprid (Merit) and acephate (Orthene). Always follow label directions for rates and safe use. It may be necessary to apply one of these pesticides every few days for complete protection. Roses may be protected by covering with light netting.

For information call your local North Carolina Cooperative Extension Service in Bladen County 910-862-4591 or come by the office and ask the publication: White Grubs in Turf.

Nancy Olsen is an agent with the Bladen County Extension Office in Elizabethtown.

Nancy Olsen

Extension agent