White grubs are the larvae of June Beetles (June bugs). June Beetles appear from May through early June in northeast Texas. The brown beetles are easy to spot outside on warm early summer nights. They lay eggs in the soil which hatch into grubs. White grubs have a yellow head with a white body and a blue or black rear end. They range in length from 1/4 inch to two inches and are shaped like a “C”.
After hatching, the grubs feed on grass roots, shearing them near the soil surface. With severed roots, the grass cannot obtain water or nutrients and dies. Infested lawns develop brown patches of grass that can be pulled up easily and rolled back like a carpet. Damage is most noticeable in late summer through fall. To check your lawn for infestation, use a shovel and cut three sides of a one-foot square in the grass about three inches deep. Lay the flap of grass back and examine the exposed soil. Repeat the process in two or three other places. If you find four or more grubs per square foot checked, apply diazinon or other appropriate granules according to product directions to control them.
The younger the grubs are, the easier they are to control, so it is a good idea to check the lawn for infestation before damage becomes visible. After application of the granules, water the lawn thoroughly to ensure that the chemical reaches the grubs.
Tom Russell, former Smith County Master Gardener
Texas A&M AgriLife Extension Service