Lawn grubs are little insects that come from the eggs of Japanese beetles. They feed on grass roots, so if an infestation occurs they can quickly turn your lawn brown and unsightly. As few as 10 lawn grubs per square foot can lead to the browning of your lawn. To prevent damage to your lawn by grubs, you need to know what type of insect to look for and how to identify lawn grub damage.
Check the affected area for white, C-shaped grubs. Gently pull back the surface layer of grass and roots to look for the grubs. When searching for potential areas, focus on areas of the lawn that are browning.
Look for damage to your lawn that may have been caused by skunks or raccoons. They will most likely dig up the lawn to search for grubs to eat.
Take a sample of your soil. Use a shovel and cut three sides of a 12-inch square. Peel back the cut area and look for grubs. Count the number of grubs in this square-foot area. Replace the soil and water the area completely. If you see more than 10 grubs per square foot, then you will have to treat your lawn for these pests.