Lawn grubs can cause serious damage to even the healthiest lawns, especially when you have a heavy infestation. A certain amount of grubs in a lawn are unavoidable, and in smaller populations they do little visible damage. If you have a more severe infestation of grubs in your lawn, there are very specific signs to look for. Understanding what is and is not a symptom of a grub infestation is vital to restoring the health of your lawn.
Irregular Patches of Brown Grass
One sure sign of grubs in a lawn is wilting, browning grass developing in irregularly-shaped patches. Because grubs usually cause the most lawn damage during mid- to late summer or early autumn, this is when you'll see these spots emerge. Beware that there are many other causes to consider when you see dead patches of grass in your lawn, such as weakly-rooting grass in shady lawn areas. Study your lawn carefully to diagnose a grub infestation. You should see that the grass is drying out faster in certain patches and that the spots started as smaller, pale areas of grass turning into the brown, wilted patches.
Beetles Flying Around the Lawn
Lawn grubs are actually the larvae of certain beetle species. If you saw beetles flying around your lawn in late spring and early summer, you might have witnessed the very beginning of your grub infestation. The adult female beetles fly around the lawn area during May, June and early July to lay their eggs in the soil.
Other Animals Attracted to Your Lawn
Often you'll see birds, particularly starlings, skunks, moles and raccoons digging in your lawn during mid- to late summer and early autumn. These animals are attracted to your lawn because they're feeding on the grubs.
Sod Peeling Up Like a Carpet
Grubs feed on the grass roots, severing the grass blades from the roots below. If you suspect a grub infestation in your lawn, try to lift up the sod in the damaged patches. If the grass lifts up easily, like rolling up a carpet, and appears to be severed from the roots, you likely have a grub infestation. When you lift up the sod, inspect the area in the soil around the grass roots for white c-shaped grubs. Count the grubs that you see in each damaged lawn area. If you have more than 10 grubs per square foot, you'll need to take action to treat the infestation.