How to Get Rid of Grubs in Your Lawn

If you’ve pulled back brown, dead patches of lawn and found the turf rolls up like a carpet — with the soil underneath revealing fat, white, C-shaped larvae — you have a grub problem. Grubs are the larval stage of several beetles, and they feed on grass roots, causing dead patches that expand through summer and fall.

The good news: grub control is one of the more straightforward lawn pest problems to solve — if you treat at the right time.

What Are Lawn Grubs?

Lawn grubs are the larvae of several species of beetles, most commonly:

Japanese beetle (Popillia japonica):

• The most destructive grub species in the eastern U.S.
• Adult beetles emerge in June–July, feed on ornamental plants (roses, linden trees, grapes), and lay eggs in lawn soil in July–August
• Eggs hatch into small larvae that feed on grass roots through late summer and fall
• Overwinter deep in the soil, resume feeding in spring, then pupate in late spring
• Adult beetles emerge again in June

June bug / May bug (Phyllophaga species):

• Native species; common throughout the U.S.
• Adults emerge in May–June; lay eggs in lawn soil
• Larvae feed through summer and fall; three-year life cycle (compared to one year for Japanese beetles)

European chafer, Oriental beetle, masked chafers: Additional species, each with slightly different timing.

How to identify grubs:

• C-shaped, creamy white larvae with brown heads and six small legs
• 3/4 to 1 inch long (Japanese beetle grubs)
• Found 1–3 inches below the soil surface in affected areas

Signs of grub damage:

• Irregular brown, dead patches in the lawn in late summer (August–October)
• Dead patches that can be lifted like carpet (roots destroyed)
• High mole activity (moles feed on grubs)
• Birds (starlings, crows, robins) probing the lawn
• Skunks and raccoons digging in the lawn at night

Confirming Grub Damage

The sod cut test: In a suspected area, use a spade to cut a 12-inch x 12-inch section of sod and flip it back. Count the grubs in the top 3 inches of soil.

Damage thresholds:

• 5–10 grubs per square foot: Significant damage possible; treatment warranted
• Less than 5 per square foot: Healthy turf typically tolerates this level without significant damage
• 10+ grubs per square foot: Treatment essential

Timing: The Most Important Factor

Timing is critical — grub treatments are dramatically more effective against young, small larvae than against large, mature grubs.

The treatment window for Japanese beetles:

• July–August: Eggs hatch; young, first-instar larvae are near the soil surface and vulnerable
• September–October: Larger larvae, still somewhat controllable with curative products
• Late fall / winter: Larvae move deep into the soil; no effective treatment
• Spring: Larvae return to surface briefly before pupating — some curative treatments applicable
• Prevention (May–June): Apply before eggs are laid; preventive products protect through egg-laying and hatching

Treatment Option 1: Preventive Grub Control (Most Effective)

Preventive products are applied before eggs are laid (May–June) and break down as eggs hatch, killing young larvae.

Best Preventive Product: Scotts GrubEx

Active ingredient: Chlorantraniliprole Application timing: May–June (before Japanese beetles begin egg-laying) Duration: Season-long protection

GrubEx is the most widely used consumer grub preventive. Chlorantraniliprole has low toxicity to birds, mammals, and beneficial insects, and provides excellent season-long control when applied at the right time.

How to apply:

1. Apply to the lawn with a spreader at the recommended rate
2. Water in thoroughly immediately after application (1/2 inch of water)
3. A single spring application protects through the entire hatching season

Price: $$ (5,000 sq ft bag, approx. $25–$35)

Alternative: Bayer Grub Killer Plus (imidacloprid) — another effective preventive; apply in May–June and water in.

Treatment Option 2: Curative Grub Control (For Active Infestations)

If grubs are already damaging your lawn (visible damage in August–October), use a fast-acting curative product.

Best Curative Product: BioAdvanced 24 Hour Grub Killer Plus

Active ingredient: Trichlorfon Works on: All grub species; effective against larger, mature grubs Timing: August–September (while damage is occurring)

Apply according to label directions and water in thoroughly. Provides kill within 24–48 hours for surface-active grubs.

Note: Trichlorfon has higher mammalian toxicity than preventive products — follow label safety directions and keep pets off the lawn until watered in and dry.

Price: $$ (10 lbs, approx. $25–$35)

Option 3: Organic/Natural Grub Control

Beneficial Nematodes

Beneficial nematodes (Steinernema feltiae or Heterorhabditis bacteriophora) are microscopic roundworms that parasitize grub larvae. They’re OMRI-listed for organic use.

Application:

• Mix with water and apply in the evening (nematodes are killed by UV)
• Apply to moist soil at 50°F+ soil temperature
• Water the lawn before and after application
• Must be used when fresh — nematodes die quickly; refrigerate until use

Best species for grubs: Heterorhabditis bacteriophora (Hb nematodes) are most effective against Japanese beetle grubs.

Apply in: Late August through September, when grubs are small and near the surface.

Best products: NaturesGoodGuys Live Beneficial Nematodes (Hb + Sc mixed species)

Effectiveness: Moderate — nematodes require specific conditions (moist, warm soil) and have shorter residual than chemical options. Plan for 40–60% reduction under good conditions.

Milky Spore (Bacillus popilliae)

A naturally occurring soil bacterium that infects and kills Japanese beetle grubs specifically. Multiplies in the soil over time.

The important caveat: Milky spore requires 2–3 years to establish in the soil at effective levels, and works only on Japanese beetle grubs — not other species.

Best products: St. Gabriel Organics Milky Spore Lawn & Garden Pest Control (granular form)

Lawn Repair After Grub Damage

After successful grub treatment, the dead patches won’t recover on their own — the root systems are gone.

Repair steps:

1. Rake out dead grass and debris
2. Loosen the top 1–2 inches of soil with a garden rake
3. Apply a starter fertilizer
4. Seed with the appropriate grass species for your region
5. Keep moist until germination (1–3 weeks depending on species and temperature)
6. Consider sod for large dead patches where a quick, no-fail repair is needed

Timing Summary

Month	Action
May–June	Apply preventive grub control (GrubEx or imidacloprid) and water in
July	Monitor for adult beetle activity; check for early grub presence in August
August–September	Apply curative treatment if 5+ grubs/sq ft are found
September	Apply nematodes as organic alternative
October	Repair dead patches with seed or sod
Following May	Reapply preventive treatment for ongoing protection

Prevention Checklist

• Apply GrubEx in May–June annually if you’ve had grub problems
• Water in all grub treatments immediately and thoroughly
• Monitor for Japanese beetle adults in June–July (they target your ornamental plants)
• Check for grub activity in August by cutting sod in suspicious areas
• Overseed or patch dead areas in September–October after successful treatment

Bottom Line

Lawn grub control is highly timing-dependent. A preventive application of GrubEx (chlorantraniliprole) applied in May–June and watered in is the most effective and lowest-effort approach — it protects through the entire egg-laying and hatching season. For active late-summer infestations (visible damage in August–September), a curative product like BioAdvanced 24 Hour Grub Killer provides fast results. Repair dead patches after successful treatment — the grass won’t regenerate on its own once roots are destroyed.