Fall Grub Damage: Skunks, Raccoons, and What to Do Now

You wake up and part of the lawn has been peeled back like a carpet. Patches flipped over, holes poked everywhere. That's not vandalism. It's skunks, raccoons, or crows hunting the white grubs living under your grass. Here's how to tell what's going on and what you can do about it in fall.

Confirm it's grubs

White grubs are the C-shaped larvae of beetles like Japanese beetles, masked chafers and European chafers. They feed on grass roots.

1. Pull on the damaged turf. Grub-damaged grass lifts up easily, like loose carpet, because the roots are eaten.
2. Cut a square foot of sod at the edge of a damaged area and peel it back. Count the grubs in the top couple of inches of soil.
3. The threshold: many extension guides consider roughly 5 to 10 grubs per square foot enough to cause visible damage in a healthy lawn. Animals will dig for fewer.

If you find almost no grubs, the digging may be animals after earthworms or other insects, which happens in moist soil, and treating for grubs won't help.

Can you treat in fall?

Partly. Grubs feed near the surface in late summer and early fall, then move deeper in the soil as it cools. Curative products (fast-acting insecticides labeled for grubs) work best while grubs are small and near the surface, usually late August through September. By mid-to-late October, grubs are moving down, and treatments become much less effective. Read the label for timing, and water the product in as directed.

Preventive products, applied in early-to-mid summer, are what actually stop grub damage the next year if you've had problems.

Dealing with the animals

Skunks and raccoons will keep digging as long as there's food. Once grubs move deeper for winter, the digging usually stops on its own. Repellents and motion-activated sprinklers help some people. Never try to handle wild animals yourself; call a licensed wildlife control service if they're denning under a porch or shed.

Repair the damage

1. Roll the turf back down where it's still alive and press it into place. Water it.
2. Rake out and reseed dead patches. In October that may be too late for fall seeding; dormant seeding in November is a good option.
3. Fill holes with topsoil.

See our guide on repairing bare spots.

Prevent it next year

• Healthy, deep-rooted turf tolerates more grubs. Mow high, water deeply, feed in fall.
• If you've had grub damage, consider a preventive product next June or July.
• Watch for beetles in midsummer. Lots of Japanese beetles in July often means grubs in the fall.

Grub damage looks terrible in October, but a lawn that's treated right next summer and repaired this fall will be back to normal by June.

Photo: Common raccoon (Procyon lotor) in a tree at Noboribetsu Onsen, Hokkaido, April 2_in_a_tree_at_Noboribetsu_Onsen,_Hokkaido,_April_2023_02.jpg) by Calistemon, CC BY-SA 4.0.

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