Dealing with Grub Worms in Central, TX
White grubs are the larvae of scarab beetles. Several other species, such as May beetles and June beetles are also present, but usually in low numbers. The Japanese beetle is consistently the most damaging grub in Texas. They have cream bodies with yellow to brown heads, brown hind parts, and six legs. Mature grubs vary from 1/4 to 1-1/2 inches, depending on the species. White grubs usually lie in a curled or C-shaped position. Billbug larvae may also be present but can be distinguished by the absence of legs.
All of the important species of white grubs in Texas have a one-year lifespan and spend about 10 months of that in the ground. The life cycle of the Japanese beetle is typical for white grubs of importance in Texas. Eggs are laid in late June and early July, and larvae hatch in July. These larvae feed on grass roots until cool weather arrives in October. In November, the grubs burrow deeper into the soil and return to the root area and begin feeding in March. Larvae pupate and adults emerge in May and early June. This life cycle is basically the same for all species, except the emergence and egg-laying for the oriental beetle is about three weeks earlier than for the Japanese beetle, and emergence and egg-laying for the green June beetle is about three weeks later. Timing of chemical applications for these two species should be adjusted accordingly. The Turfgrass ataenius has two generations per year, overwintering as an adult and developing a second generation of adults by July, so they may require two treatments. Green June beetle larvae are also different in their feeding behavior. Instead of attacking grass roots, these grubs feed mainly on decaying vegetation. Their burrowing smothers grass and uproots seedlings. Sometimes in the fall or after a heavy rain, green June beetle larvae come out of the soil and crawl on their backs on the surface of the ground. They can be identified by this unusual behavior and by distinct dark spots, one per segment, on each side of the body.
White grubs can be controlled in a timely and economical manner if proper controls are correctly applied at the right time. To prevent serious damage, examine all turf in April and again in August for the presence of grubs. Birds, moles, skunks and raccoons all feed on grubs, and their digging in the lawn may be a sign of a white grub infestation. However, it is best to verify that grubs are actually present before applying pesticides. Use a knife or spade to cut a 1-square-foot flap of sod and roll it back. Examine the soil and roots in the top 3 or 4 inches. Repeat this process in several locations. If you find an average of five or more grubs per square foot, a pesticide application is justified. The condition of the turf, its value, and its uses (for example, whether it is a home lawn or a golf green), and the amount of damage done by animals searching for the grubs may affect your decision on whether to apply a pesticide.