Grubs and other listed insects can do extensive damage to lawns by feeding on grass roots. Damaged turf turns brown and is easily pulled up by hand. Prevent turf damage with Scotts GrubEx1 Season Long Grub Killer. A single application of this granular insecticide can kill and prevent grubs for up to 4 months. This grub killer also kills caterpillars (armyworm), chinchbugs, May/June beetles, and more (as listed), and can help control Japanese beetle infestations when applied annually. Apply to a dry lawn in the spring or early summer to kill grubs as they develop. Manufacturer recommends using a spreader to apply this product. Water in thoroughly to activate. People and pets may re-enter the lawn after it has dried.