Grub worms can be a nuisance to any lawn, so it's important to know how to get rid of them. Grub worms, the larval stage of the Japanese beetle, feast on the roots of grass and other plants, and are a real headache for gardeners. Unfortunately, grub worms live with the desirable earthworm so care must be taken to kill only the grub worms while maintaining conditions that will allow the earthworms to continue to thrive.
The first sign of a grub worm infestation is usually patches of lawn that yellow and die. You might also see patches of brown lawn that pull away from the soil easily. Increased populations of birds, moles, raccoons, wasps, and in some locations, armadillos, indicate a white grub infestation. To verify, dig up three to four inches of soil and look for the white grubs.
Your first offense is water. Earthworms like a moist but not wet environment; grubs want wet soil. Water carefully, to provide the moist soil for the earthworms, and the grubs will move on. This option takes some time but also protects beneficial natural predators that prey on the grub worms..
There are several organic treatments for grub worms that will not harm the beneficial organisms and insects in your soil. Milky spore is a disease the affects grub worms but does not harm other creatures or the environment. Apply the spores to the infected areas. As the grubs die, their bodies will decompose and release spores into the surrounding area, helping to protect it from further infestations.
Neem oil is a botanical pesticide with insecticidal features. It repels the grubs, the adult Japanese beetles, and inhibits egg-laying, growth, and feeding. Dilute with water as directed on the label and spray on the affected areas.
Nematodes, tiny soil-dwelling worms, are available in liquid forms to be sprayed on the affected areas. Once established, they release bacteria into the soil that kills the grub worms.