Lawn or White Grubs In Gardens and Lawns

- The larval stage of certain scarab beetles -

Summary: Lawn grubs, or white grubs, are the larval stage of scarab beetles. These larvae feed on the roots of plants often causing significant damage. Grub control is sometimes necessary in lawns and gardens and frequently necessary in golf courses where the management of this turf pest is critical.

Jack DeAngelis, PhD

OSU Ext. Entomologist (ret.)

Identification of white grubs

White grubs (right) are the larval stage of certain beetles, called scarabs (family: Scarabidae). Japanese beetles and June beetles (June bugs) [photo of June beetles] are familiar examples of scarab beetles. The larvae (grubs) live in the soil where they feed on organic matter and plant roots. Damage is done when larvae eat the roots of plants and grasses leaving them unable to obtain water and nutrients. Adult beetles, like Japanese beetle, can also damage the leaves of host plants.

White grubs are easy to identify. They are fairly large, creme-colored larvae with 3 distinct pairs of legs and an amber-colored head. The tail end of the larva is often packed with soil particles, visible as a dark mass, and the body is often bent into a "C" shape (see photo, right).

common names & misnomers: whitegrubs

White/lawn grub larva photo by Steven Katovich, USDA Forest Service, www.forestryimages.org. Notice legs, amber-colored head and soil packed into tail end of this larva.

Turf damage caused by lawn grubs

Because white grubs feed on roots, damage is usually first noticed during dry periods when injured plants cannot get the water they need. Turf often dies in large, irregular-shaped patches. Birds and other predators may damage turf as well as they dig in order to prey on white grub larvae in the soil.

How to stop lawn grub damage at home and golf courses

Golf course turf managers and other folks responsible for commercial turf areas generally resort to soil-applied insecticides to control infestations of lawn grubs. Imidacloprid (Merit Insecticide, Bayer Advanced; see What is Merit Insecticide?) is one of the more commonly used insecticides for this application. Other materials and specific control recommendations can be found here (DoMyOwn.com, one of our affiliates)

For most homeowners, however, it is better to focus on improving turf health through proper watering and fertilization, and use of the natural microbial insecticides Milky Spore and/or entomopathogenic nematodes. Milky Spore (also called Milky Disease) is a natural soil bacterium that infects and kills grubs. It is commonly used for Japanese beetle control but also works for other turf-damaging lawn grub species. Milky Spore for lawn grub control is available here (DoMyOwn.com, our affiliate).

Entomopathogenic nematodes are also a natural component of most soils. These tiny hunters attack white grubs and kill the larvae, see Using Nemtodes For Grub Control.

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