To rid your lawn of grubs, first verify that you have a grub infestation by lifting up a patch of dying grass and looking underneath. After establishing that your lawn is infested, treat the lawn with nematodes, or use a brand called Milky Spore.
To check for infestation, cut three sides from a square foot patch of dead grass with a shovel, and pull it back. An indication of infestation is that the grass roots are easy to lift up. If you can count more than five grubs underneath the patch, there is likely an infestation.
To treat a grub problem, use nematodes, which are microscopic worms that are purchasable from lawn and garden stores or online garden supply catalogs. Nematodes feed on grubs by penetrating through grubs and transmitting a bacteria that breaks down grub tissue. You can apply nematodes through a sprayer. Nematodes are harmless toward people and other insects.
Milky Spore is a product available at garden supply stores that is made up of the bacteria Bacillus popillae, which only attacks grubs and allows beneficial insects to thrive. To apply the product, sprinkle it onto the grass or spray it using a hose. Apply Milky Spore during the spring or fall to ensure the best results. The product may last 10 to 15 years after conforming to the lawn.