Scarabaeidae
From Bugwoodwiki
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Author: Dr. Steve L. Brown, Dr. Will Hudson, University of Georgia
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Description
White grubs are the larvae of Scarab beetles. There are more than 20 species of these beetles whose grubs might be found damaging plants in Georgia. The adults are fairly heavy-bodied insects; most with long, spindly legs. They range in color from light, reddish-brown to shiny black and in sizefrom ½ inch to over 1" in length. The grubs are white with a brown head and legs and with a darker area at the tip of the abdomen. They curl up in a C-shape when disturbed. Fully grown grubs of larger species are 1" or more in length.
Hosts
Roots and foliage of many plants, including grasses, ornamentals (trees and shrubs), shade trees, and fruit trees.
Damage
Grubs feed on the roots of plants, and also cause mechanical damage as they tunnel through the soil. Adults of some species feed on foliage of a variety of shade trees, fruit trees, grapes and other deciduous plants.
Life Cycle
Most white grubs in Georgia have a 1-year life cycle. Adults emerge from the soil in late spring or early summer, depending on the species. They feed, mate, and return to the soil to lay eggs. Grubs hatch out and feed until cold weather sends them deeper to overwinter as mid-sized (2nd instar) larvae. They return to the root zone when the soil warms in the spring and feed until they mature. Pupation occurs in the soil. In north Georgia, some species may take 2 years to complete this life cycle.
Control
As with other soil dwelling pests, control with insecticides is difficult. Best results occur when treatments are applied to young grubs, generally in August. Larger grubs are more difficult to control and may require more than one treatment. Management of soil moisture will improve results.
