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If you’ve ever grabbed a patch of brown grass and had it peel back like loose carpet — roots gone, soil exposed — you already know what grub damage feels like. Knowing how to get rid of grubs in lawn comes down to one thing most homeowners get wrong: timing. The right product at the wrong time of year does almost nothing. Here’s how to do it right.
What Are Lawn Grubs?
Grubs are the larvae of beetles — most commonly Japanese beetles, June bugs, and masked chafers. They live just below the soil surface and feed on grass roots from late summer through fall, then burrow deeper to overwinter and emerge as adult beetles the following spring and summer. The cycle repeats every year.
The larvae are easy to identify: white, C-shaped, about the size of your thumbnail, with a brown head. If you dig down 2–3 inches in a damaged area and find six or more per square foot, you have a grub problem worth treating.
How to Get Rid of Grubs in Your Lawn — Know Your Window
This is where most homeowners waste money. There are two types of grub treatments and they work in completely different windows:
Preventive Treatment (May–July)
Preventive grub killers contain imidacloprid or chlorantraniliprole and are applied before eggs hatch. They sit in the soil and kill young larvae as they emerge. Scotts GrubEx1 is the most widely used preventive — apply it in May or June before adult beetles start laying eggs, water it in well, and it protects your lawn for the season. This is the right product if you’re being proactive or had grub damage last year.
Curative Treatment (August–September)
If grubs are already active and eating your roots right now, you need a fast-acting curative product. Ortho BugClear Lawn Insect Killer works within 24 hours and kills grubs that are already in the soil. Apply it, water it in deeply (at least half an inch), and give it a week to work through the soil. Curative treatments are less effective on large grubs late in fall — the earlier in August you catch it, the better.
How to Know If You Have Grubs (Not Just Drought or Disease)
Grub damage is often mistaken for summer dormancy or drought stress. Here’s how to tell them apart:
The Tug Test
Grab a handful of brown grass near the damaged area and pull. If it peels back easily with no root resistance — like pulling up a piece of loose sod — grubs have eaten the roots and that’s your answer. Dormant or drought-stressed grass resists pulling because the roots are still intact.
The Dig Test
Cut a 1-square-foot section of sod about 3 inches deep at the edge of a damaged area and fold it back. Count the grubs. The treatment threshold is generally 6–10 grubs per square foot for most grass types. Fewer than that and the lawn can typically outgrow the damage on its own.
Look for Secondary Evidence
Skunks, raccoons, and birds digging up your lawn overnight are a strong sign of grubs underneath — they can smell them. If you’re finding torn-up turf in the morning with no other explanation, dig down and check.
Not sure if it’s grubs or something else? Our what’s wrong with my lawn guide covers lawn disease, fungus, and other common causes of brown patches.
How to Treat Grubs Step by Step
Step 1 — Confirm the Infestation
Do the dig test first. Don’t treat if you’re under threshold — unnecessary pesticide application isn’t good for your lawn or your soil biology.
Step 2 — Choose the Right Product for the Time of Year
May–July: use a preventive like Scotts GrubEx1
August–September: use a curative like Ortho BugClear Lawn Insect Killer
Step 3 — Apply and Water In
Both products require water activation. Apply granular products with a spreader and water in with at least a half inch of irrigation immediately after. Liquid products like Ortho BugClear should also be watered in after application. Dry application without watering is the number one reason grub treatments fail.
Step 4 — Wait and Reassess
Give the treatment 2–3 weeks before re-evaluating. Dead grubs decompose in the soil — you won’t always see them on the surface. What you’ll notice is that the damaged areas stop expanding and the surrounding lawn stays healthy.
Step 5 — Repair the Damage
Once grubs are under control, press any lifted turf back down firmly with a lawn roller. Fill it with water for weight, roll the affected areas, and the roots that are still partially intact may reestablish if watered consistently. For areas where roots are completely gone, you’ll need to reseed.
For bare patches that need fresh seed, our guide on how to overseed a lawn covers the full prep and aftercare process.
Step 6 — Reseed Bare Areas
Rake out any dead material, loosen the top inch of soil, and spread grass seed at the overseeding rate for your grass type. Keep the seed moist twice daily until germination. Fall is the ideal window for cool-season grass repair — soil is still warm and air temps are dropping, which is exactly what cool-season seed needs.
Will Grubs Come Back Next Year?
Probably, if you have adult beetles in your area — and most of the Midwest and Northeast do. The best long-term strategy is a preventive treatment every spring before beetles lay eggs. One application of GrubEx in May or June covers the entire season and is far easier than dealing with damage in August.
What Doesn’t Work
Milky spore (a biological control) is frequently recommended online but only targets Japanese beetle grubs, takes 2–3 years to establish, and is largely ineffective in colder climates. Nematodes require very specific soil temperature and moisture conditions to survive long enough to work. Neither is a reliable fix for an active infestation. Stick with proven chemistry for curative treatment and save the biological options for long-term prevention experiments once your lawn is healthy.