White grubs are damaging little pests that feed on the roots of grass and create lawn damage. Liquid grub killers are designed to kill these pests at all stages of their life, both before and after they are born. White grubs live in soil and may be difficult to spot with the naked eye; they move down into the soil to survive the winter.
Early Season Pesticides
Apply preventative insecticides in early spring to kill grubs before they appear. Insecticides containing halofenozide and/or imidacloprid are effective in killing grubs before they begin to damage the lawn. Avoid applying treatment too early in the season; look for adult beetles to know when to use the treatment. In most cases, these liquid killers may be applied to the lawn between April and August.
Late Season Pesticides
Once grubs have started to damage the lawn, apply late-season pesticides to kill them. Liquid insecticides containing trichlorfon and/or carbaryl are effective in killing grubs that are already feeding on your lawn. Late-season pesticides may be applied to the soil in fall to kill wintering grubs and prevent them from returning to the lawn next spring.
Always apply pesticide with water. Thoroughly wet the soil 1/4 to 1/2 inches before spraying liquid insecticide. Watering the soil allows the insecticide to penetrate the area where grubs live. Unless you are using preventative pesticide, treat only the affected area. Repeat applications of pesticide may be needed before all grubs have been killed.
Liquid milky spore may be used in place of pesticides to kill grubs. Milky spore is a bacterial disease that kills grubs, but it will not be wholly affective against high grub populations. Bacteria is a living organism, and will repeat a cycle of life and death in your lawn once it has been introduced. The milky spore will become a long-lasting, repeat killer of unwanted grubs. Milky spore is available in liquid form in garden centers.