Several types of beetles, most notably the Japanese beetle, lay their eggs in your lawn soil. Come summer, these eggs hatch into small white grubs that feed on the roots of your lawn grass. Without proper monitoring and treatment, a grub infestation can quickly destroy your lawn's green appearance. In addition, if they're not killed at the larvae stage, the grubs will hatch into hungry beetles with an appetite for your vegetable garden and ornamental plants.
Cut out a 1/2-square-foot section of your sod with a spade. Pull back the grass and inspect the soil. You only need to treat your lawn for grubs if you find five or more grubs squirming in the dirt.
Trim your grass with a lawnmower. This will help the chemical grub treatment better penetrate the soil. Cut the grass to the height that's best for your specific grass species. For example, ryegrasses are typically cut to approximately 2 inches while hybrid zoysiagrass is usually cut to 1/2 to 1 inch. If you're unsure, consult a nursery or garden store.
Spray your lawn with a chemical insecticide formulated with acephate, permethrin or carbaryl. Such products can be purchased from most garden stores. Apply the spray according to the instructions on the label, as toxicity varies by product and manufacturer.
Inspect your lawn again four to six weeks later to see if re-treatment is necessary.