If you notice some patches of brown in your lawn, you may have white grubs. White grubs hatch from eggs laid by the Japanese beetle. They eat the roots of your lawn grass. This causes the grass to dry up and change from green to brown. Instead of treating your lawn with chemicals, you can use an all-natural predator of white grubs: nematodes.
Wait for the soil temperature to remain above 70 degrees F. The nematodes will be more active and will kill the white slugs much quicker if the temperature of the soil remains warm.
Purchase Heterorhabditis bacteriophora nematodes. You can get them through your local gardening center, or order them online if your gardening center does not carry them.
Apply the nematodes based on the package instructions. This is usually at a rate of 1 billion nematodes per acre of land.
Water your lawn until the water has penetrated the soil at least a 1/4 inch down. This will send the nematodes down into the soil where the white grubs are living.