Grubs are perhaps the most hated pest insect in the country. They are often blamed for lawn problems in error. This file should help you be sure that your problem is in fact caused by grubs and then if that is the case, we will help you solve that problem once and for all.

“Grub” is a catch-all term for the larval, or worm, stage of many kinds of beetles. May beetles (also called June bugs), Japanese beetles, masked chafers, billbugs, Asiatic garden beetles and others all are grubs in the soil prior to emerging as beetles during the growing season. In the Northeast, Japanese beetle grubs are the most common pests of residential lawns. Masked chafers are most common in the Midwest, and June bugs are most common in the West.

Where Grubs Are Found

Grubs are plump whitish colored worms that grow 3/4 to 1-1/2 inches long. They have 3 pairs of legs and tan heads with large, brown-black mouth parts. They rest in a characteristic C-shaped curl just under the soil surface in planted areas or turf, where they feed on roots of ornamental plants and lawn grasses. In vegetable gardens grubs are not usually a problem because they are exposed when the soil is frequently disturbed by cultivation and planting. However, they may infest new planting areas that have been established where there was once lawn.

Growth Stages Of Grubs

An understanding of a grub’s life cycle--which may span 1, 2, or even to 3 years, depending on the species--is the foundation of a successful control strategy. During the summer the adult beetles leave the soil at dusk and fly about during the night feeding on tree and shrub foliage and mating. At dawn, the beetles fly back to the soil to lay their eggs. The eggs hatch in 2 or 3 weeks, and the new grubs feed on roots and other underground plant parts until early fall. Then they burrow deep into the soil to hibernate below the frost for the winter. As the weather and soil warm up in the spring, grubs migrate back toward the surface to resume feeding on plant roots. They feed all season long and then dig down again to overwinter. Next season they come back up, feed, pupate, and emerge as adult beetles.