They have brown heads, three pair of legs and lie curled in the soil. When the eggs hatch, grubs feed down 1 to 3 inches in the soil on grass roots. They can survive the winter by burrowing deep into the soil, and when thaw comes in the spring they will begin feeding again. Apply an insecticide containing diazinon, chlorpyrifos or isofenophos when you first notice the grub damage in your lawn. The younger the grubs, the easier they are to kill off.
Preventative control consists of applying the insecticide just after eggs are laid.
You can find out the proper time to do this by contacting your local cooperative extension office. After applying insecticide, thoroughly water the lawn to be sure the insecticide hits the root zone. Grubs often remain active up to 30 days after treatment, and occasionally successive treatments may be necessary to completely eradicate the grubs. It could be lawn grub damage from one of several beetles. Find out what they are how to control them.