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White Grubs In Lawns
- The larval stage of ornate beetles -
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Summary: White grubs are the larval stage of scarab beetles. These larvae feed on roots often at damaging levels. White grub control is often necessary in managed turf areas like golf courses.
Jack DeAngelis, PhD
OSU Ext. Entomologist (ret.)
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What are white grubs?
 White grubs (right) are the larval stage of certain beetles, called scarabs (family Scarabidae). Japanese beetles and June beetles are familiar examples of scarab beetles.
White grubs are easy to identify, at least to the family level. 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 generally packed with soil particles, visible as a dark mass, and the body is often bend into a "C" shape (right).
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| White grub larva photo by Steven Katovich, USDA Forest Service, www.forestryimages.org |
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White grubs live in the soil where they feed on organic matter and plant roots. Damage is done when larvae strip the roots off plants, often grasses. Adult beetles, like Japanese beetle, can also damage the foliage of host plants.
common names & misnomers: whitegrubs
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Turf damage caused by white 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 in order to prey on larvae in the soil.
Can I limit white grub damage?
Managers of golf courses, and similar commercial turf areas, generally resort to conventional soil-applied insecticides to control infestations of white grubs. Imidacloprid (Merit Insecticide, Bayer Advanced) is one of the more effective conventional insecticides for this application. A relatively new product, Allectus, combines imidacloprid with bifenthrin.
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| Most homeowners, however, will do better focusing on improving turf health through proper watering and fertilization, and use of the natural microbial insecticides Milky Spore and entomopathogenic nematodes. Milky Spore (milky disease) is a natural soil bacterium that infects and kills white grubs. It is commonly used for Japanese beetle control but also infects other turf-damaging white grub species. Entomopathogenic nematodes are also a natural component of most soils. These tiny hunters infest white grubs and kill the larvae. The nematodes can be easily applied to infested turf to augment the natural population.
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