The Effects of Grub Worms on Grass

White Grub Damage

• Gardeners with white grub damage may notice patches of dead grass. In addition, you may see raccoons and other wildlife digging up your lawn to get to the grubs. A high population of white grubs can result in grass that can be rolled up like carpeting. Furthermore, grass may feel bouncy as you walk across the lawn, according to the University of Florida. Healthy, densely growing grass with a moderate white grub population typically bounces back from the damage.

Testing

• Cut out 1 square foot of turf from the lawn with a masonry trowel to determine the severity of your white grub problem. If you find more than 10 grubs in the grass or dirt, use a pesticide to treat the problem. You can control grubs through cultural practices if there are less than 10 in the turf patch. Gardeners may be tempted to treat grubs in the spring. However, late-summer pesticide applications are more effective because grubs have just hatched.

Cultural Treatment

• Beetles look for moist soil to lay their eggs, so a dry lawn in the late summer is essential. Also, restricting water on your lawn will dry out the eggs. Gardeners can also check their thatch layer to see if it is more than 1/2 inch. If it is, it creates an optimal environment for grubs. If you decide to use pesticides, it is better to remove thick thatch so that the chemicals can be absorbed into the soil. Dethatch the lawn to remove grubs' environment and prepare the lawn for potential pesticide use.

Chemical Treatment

• Pesticides that contain imidacloprid or halofenozide should be applied between Aug. 1 and Sept. 15, according to the University of Rhode Island. Apply the pesticide in the most severely damaged areas of the lawn. Water the pesticide after applying with 1/4 to 1/2 inch of water so that it sinks into the soil. You can also forgo watering if afternoon showers are expected. Reapply the pesticide as recommended on the label.