Ways to deal with grubs, Japanese beetles

Calls are coming in about grubs in the soil. Right now the grubs are quite large and are harder to control than if it were the end of August or first part of September when the grubs are quite small.

Grubs feed on roots in the ground in the spring and Japanese beetles feed on plant vegetation usually from the last of May into July. When your plants are being eaten from leaf to flower and your garden is being invaded by metallic green and copper beetles, then you most likely have Japanese beetles.

Japanese beetles are about ½-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 to 1 1/2 inches 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. They are present especially 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 June. Throughout summer, the Japanese 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 on shallow grass roots until cold weather forces them into hibernation. This is the best time to control grubs as it takes less chemical to kill the grub. One generation occurs each year.

Soil insecticides may be used in late summer or early fall to control grubs feeding near the soil surface. 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 the North Carolina Cooperative Extension Service in Bladen County at 910-862-4591 or come by the office at 450 Smith Circle Drive in Elizabethtown.