How to Get Rid of Lawn Grubs

Lawn grubs are the white, C-shaped larvae of beetles — Japanese beetles, June beetles, chafers — and they feed on grass roots just below the surface. A bad infestation kills patches of turf that peel up like loose carpet, and the secondary damage from skunks, raccoons, and birds digging for the grubs is often worse than the grubs themselves. The key to control is timing: you have to match the treatment to the grubs’ life stage, because what kills young grubs in late summer barely touches the big, leathery grubs you find in fall and spring. This guide shows how to confirm you actually have a grub problem, when to use preventive versus curative products, and the organic options that work.

Signs You Have a Grub Problem

Grub damage looks a lot like drought at first — irregular brown patches that don’t green up after watering. The tell is that grub-damaged turf has no roots holding it down, so it lifts up like a rug when you tug it. Other warning signs:

• Spongy, soft areas that feel like walking on a thick pad.
• Sudden digging by skunks, raccoons, armadillos, or flocks of birds — they’re eating the grubs.
• Increased beetle activity (Japanese beetles, June bugs) over the lawn in early-to-mid summer, signaling egg-laying.

Confirm the Threshold Before Treating

A few grubs are normal in any lawn and don’t warrant chemicals. Confirm the population before spending money or applying insecticide. Cut three sides of a 1-foot-by-1-foot square of turf and fold it back like a flap. Count the white, C-shaped grubs in the top few inches of soil, then fold the turf back and water it in.

The general threshold is 6 to 10 grubs per square foot. Healthy, well-watered lawns tolerate up to about 10; stressed or thin lawns may show damage at 5 or 6. Below that count, do nothing — the grass will outgrow the feeding. Sample a few spots, especially near damaged edges, to get an honest average.

Sampling well matters because grubs are patchy—they cluster where beetles found the lawn attractive for egg-laying, often in sunny, irrigated, open turf. Check at least three or four spots across the lawn rather than judging from a single flap, and concentrate on the margins of visibly thinning or browning areas rather than the dead center, where the grubs may have already moved on or starved out. Time your sampling for late summer or early fall, when the grubs are present and feeding near the surface; a midsummer dig may find only eggs or freshly hatched larvae too small to count reliably, and a spring dig may turn up the big, nearly mature grubs that are hard to kill anyway.

Understanding the Grub Life Cycle

Most lawn grubs run on a one-year cycle. Adult beetles lay eggs in the soil in early-to-mid summer (roughly June-July). Eggs hatch in mid-to-late summer, and the tiny new grubs feed voraciously near the surface through late summer and early fall — this is the easiest stage to kill. As soil cools, grubs burrow deep to overwinter, then return to the surface to feed briefly in spring before pupating into beetles. The big grubs you find in spring are nearly done feeding and are tough to kill, which is why spring is a poor time to treat.

Preventive vs. Curative Treatments

Preventives (best for known recurring problems)

Preventive insecticides kill the grubs as they hatch. Apply them before egg hatch — late spring to early summer (May through July). The active ingredients are imidacloprid and chlorantraniliprole (the latter is lower-toxicity and bee-safer, but needs to go down earlier because it moves slowly). Preventives are the right call if your lawn was hit last year or beetles swarm your yard every summer. They will not rescue a lawn that’s already full of large grubs.

Curatives (for an active infestation)

If you’ve already confirmed grubs at threshold, you need a fast-acting curative. Carbaryl and trichlorfon kill grubs on contact in the soil and work best on young grubs in late summer to early fall. Apply at the labeled rate, and crucially, water it in with about 0.5 inch of water immediately so the product moves down to the root zone where grubs feed. Mow first and keep kids and pets off until it’s watered in and dry.

How to Apply Grub Treatments Correctly

Whether you choose a preventive or a curative, application technique decides whether it works. Granular products are the easiest for homeowners: load a broadcast or drop spreader, set it to the rate printed on the bag for your square footage, and apply in two passes at right angles to each other for even coverage. Liquid concentrates that attach to a hose end cover ground fast but are harder to apply evenly. The non-negotiable final step for nearly every grub product is watering it in—about half an inch—immediately after application, because the active ingredient has to move down through the thatch into the top few inches of soil where the grubs actually feed. A product left dry on the surface does almost nothing. Always measure your lawn’s area first so you apply the correct rate; under-applying wastes the treatment and over-applying risks harm to soil life and runoff.

Common Grub Beetles and Regional Timing

Knowing which beetle you’re dealing with helps you predict timing. Japanese beetles are the most widespread troublemaker across the eastern and central US; adults emerge and lay eggs in early-to-midsummer, and milky spore works specifically against their grubs. Masked chafers produce the annual white grubs common in lawns from the Midwest eastward, on a similar one-year schedule. June beetles (May/June bugs) can run on a two- or three-year cycle in cooler regions, so large grubs may appear out of the usual rhythm. European chafers are particularly damaging in the Northeast and upper Midwest because their grubs feed later into fall and earlier in spring than other species. Across all of them, the practical takeaway is the same: scout for adult beetles in early summer as your cue that egg-laying is underway, then plan a curative pass for late summer when the young grubs are small and vulnerable.

Organic and Long-Term Control

If you’d rather skip synthetic insecticides, two biological tools work:

• Beneficial nematodes (Heterorhabditis bacteriophora) are microscopic worms that hunt and kill grubs. Apply them to moist soil in the evening (they’re killed by UV and drying) in late summer when grubs are small, and keep the lawn watered for a couple of weeks.
• Milky spore (Paenibacillus popilliae) is a bacterium specific to Japanese beetle grubs. It’s slow — taking a few seasons to build up in the soil — but once established it can suppress that species for years. Note it does not control chafers or other beetle species.

A thick, deep-rooted lawn also resists grub damage far better than a thin one, so proper watering and mowing are part of the defense. After treatment, repair any dead areas using the steps in our guide on fixing bare spots. For more lawn-pest and yard guides, browse the Outdoor Living hub.