Grubs in your lawn? How to spot them and what to do

The signs

Brown, dead patches that show up in late summer, fall or early spring. Grass that lifts up like a loose carpet because the roots underneath have been eaten. Skunks, raccoons and birds tearing up the lawn, looking for grubs to eat.

Check for yourself

At the edge of a brown patch, cut three sides of a square about a foot across and peel the grass back. Grubs are white, C-shaped and about the size of a fingernail. A few are normal in any lawn. More than about 5 to 10 in a square foot is usually enough to do damage.

Why the damage shows up when it does

The beetles lay their eggs in lawns in early summer. The grubs hatch and eat roots from late summer into fall, move deeper into the soil for winter, then come back up and feed again in spring. That's why lawns brown out in those two seasons.

Treatment in Ontario

Ontario restricts most chemical pesticides for cosmetic lawn use, so the usual treatment here is beneficial nematodes: tiny worms, watered into the lawn, that hunt grubs in the soil. They work best in late summer and early fall, while the grubs are young and close to the surface, and the lawn has to be kept damp before and after.

Fixing the damage

If the grass is only thin, raking out the dead patches and overseeding can bring it back. If big areas are dead, new sod is the faster fix: the old lawn comes out, the ground is levelled and fresh sod goes down.

Keeping them away

A thick, healthy lawn is the best defence. Mow high, around 3 inches, and water deeply but less often. Thin, short, dry lawns are where the beetles like to lay their eggs.

Not sure it's grubs?

Brown patches can also come from drought, dog spots or lawn disease. We check at the free estimate and tell you straight what's going on. Call or text 519-567-4724.