Lawn grubs are white, C-shaped insects about 1/2 inch to 1 1/2 inches long with brown tips on both ends. They feed on the roots of grass, causing spreading patches that can often be pulled up from the soil. These insects can be found at the root level of lawn grass around the browned, affected areas. Information about the wide variety of grub killers that are available will help homeowners choose the best product for their needs.
Biological grub killers are those that use natural predators and diseases to help eliminate these garden pests. Milky spore is a bacterium called Paenibacillus popillae, which comes as dust that is applied to affected areas of grass. The grubs consume the spore material, which reproduces inside their bodies, and then the grubs die. Milky spore is not effective on all types of lawn grubs. Best effective use of this product is on the grubs of Japanese beetles, according to Alabama Cooperative Extension entomologist Patricia P Cobb.
Beneficial nematodes are small, worm-like creatures that invade the bodies of grubs and release a bacterium that kills the grub. The nematodes come in a spray solution that is applied to the lawn area. The spray contains live nematodes and must be used as quickly as possible after purchase. The Heterorhabditis bacteriophora nematode is known to be effective against lawn grubs, according to the University of Illinois site. Beneficial nematodes are the best choice for those concerned about the effects of pesticides on humans and the environment.
Effective on larger grubs later in the season, chemical lawn grub killers are considered a curative pesticide more than a preventative measure; carbaryl provides good control of grubs of Japanese beetles chafer beetles and is applied in liquid or granular form and then irrigated down to the root level to kill the grubs. The grubs will be eliminated in 10 to 14 days, according to Michigan State University writer Terry Davis.
Halofenozide is a chemical insecticide used as a preventative to kill newly-hatched grubs. Timing is important when using this product as it will degrade if applied too early before the grubs have hatched. It should be applied before July 15 to allow rainfall to soak it into the soil in preparation for the grubs’ emergence.
A chloronicotinyl type of insecticide used as a preventative grub killer is imidacloprid, which is applied early in the season to eliminate young grubs as they emerge. Treat only in and around affected areas of grass. Lawns infested with larger grubs later in the season may require a stronger, quicker-acting insecticide.