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White Grub Management in Turf

White grubs are immature scarab beetles. They hatch from eggs laid in the soil, have three larval instars, and also pupate in the soil. The third instar is often the most damaging and may be present in the soil the longest. The adults are rarely turf pests, but some may feed on tree leaves or make mounds in the soil. White grubs may have one or more generations each year in Florida.

Signs of Infestation

When white grubs feed on grass roots, the grass gradually thins, yellows, and dies. This makes the grass feel soft and spongy. Scattered, irregular, brown patches of grass appear, which increase in size over time. The root injury reduces the turf’s ability to take up water and nutrients and withstand drought stress. Heavily infested grass pulls up easily.

Problems with White Grubs

In addition, white grubs attract moles, raccoons, armadillos, and birds, which can make an already damaged area look worse. However, these animals may be interested in earthworms or other insects besides grubs. Large numbers of dark-colored, parasitic wasps with yellowish to white stripes on their abdomens that hover over the lawn on sunny days in the summer or fall may also be a sign of infestation. Sample the area to confirm that a white grub problem really exists.

(Source: UF)