4 Ways To Get Rid Of Grub Worms In Your Lawn

Grub worms are one of the most destructive lawn pests in North America. These C-shaped white larvae feed on grass roots below the soil surface, causing brown patches that peel away like carpet. Left unchecked, a grub infestation can destroy an entire lawn in a single season. Here’s how to identify, treat, and prevent grub damage effectively.

What Are Grub Worms?

Grub worms are the larval stage of various beetle species that complete their life cycle in your lawn.

Common grub species:

Japanese beetles: Most common and destructive; white grubs with brown heads, 3/4 to 1 inch long
June beetles (May/June bugs): Larger grubs (up to 1.5 inches), slower feeders
European chafers: Similar to Japanese beetle grubs but slightly smaller
Masked chafers: Smaller grubs, less damaging but still problematic
Oriental beetles: Smaller grubs, prefer sandy soils

Life cycle:

Summer (June-August): Adult beetles emerge, mate, and lay eggs in soil
Late summer-fall (August-October): Eggs hatch; young grubs feed aggressively on grass roots
Winter: Grubs burrow deep (6-12 inches) to avoid freezing
Spring (April-May): Grubs move back to root zone, feed briefly before pupating
Early summer: Pupae transform into adult beetles; cycle repeats

Why grubs damage lawns:

Feed exclusively on grass roots in the top 2-3 inches of soil
Sever roots from grass blades
Grass can’t absorb water or nutrients
Damage appears as brown, dead patches
Turf lifts away easily (no root anchoring)

Identifying Grub Damage

Recognizing grub damage early allows for effective treatment.

Visual symptoms:

Irregular brown patches: Dead or dying grass in random areas (not drought patterns)
Spongy turf: Lawn feels soft and spongy when walked on
Turf rolls back: Grass peels away like carpet or sod (no root resistance)
Increased bird activity: Crows, starlings, and robins digging for grubs
Animal damage: Skunks, raccoons, and armadillos tearing up lawn to feed on grubs
Timing: Damage most visible late summer through fall

How to confirm grubs:

Dig a test section: Cut three sides of a 1-foot square of turf
Peel back sod: Lift turf and examine soil surface
Count grubs: Look for white, C-shaped larvae with brown heads
Check multiple spots: Test 3-4 areas in damaged and healthy zones

Threshold levels (grubs per square foot):

0-4 grubs: Normal population; no treatment needed
5-9 grubs: Moderate infestation; monitor closely
10+ grubs: Heavy infestation; treatment required
15+ grubs: Severe damage imminent; treat immediately

Time of year considerations:

Late summer/early fall (August-October): Best time to find grubs; they’re feeding near surface
Late spring (April-May): Grubs active but about to pupate (treatment less effective)
Winter: Grubs deep underground (impossible to find or treat)

Method 1: Beneficial Nematodes (Organic Treatment)

Microscopic roundworms that parasitize and kill grubs naturally.

What are beneficial nematodes?:

Microscopic worms (invisible to naked eye)
Species used: Heterorhabditis bacteriophora (Hb) and Steinernema carpocapsae (Sc)
Hunt grubs in soil, enter their bodies, release bacteria
Bacteria multiply and kill grub within 24-48 hours
Nematode reproduces inside dead grub, releases thousands more
Cycle continues until grubs eliminated

Effectiveness:

Japanese beetle grubs: 80-90% control with Hb strain
June beetle grubs: 60-80% control
European chafers: 70-85% control
Works best on young grubs (early instars)

When to apply:

Best timing: Late summer to early fall (August-September)
Soil temperature 50-90°F (nematodes die outside this range)
Apply when grubs are small and actively feeding near surface
Can also apply in late spring if you missed fall window

How to apply beneficial nematodes:

Purchase fresh nematodes:
- Buy from reputable suppliers (check expiration date)
- Store refrigerated until use (don’t freeze)
- Use within 2-3 weeks of purchase
- Common brands: NaturesGoodGuys, Arbico Organics, Grub Grenade
Prepare application area:
- Mow lawn to 2-3 inches
- Water lawn thoroughly day before (soil must be moist)
- Apply in evening or on cloudy day (UV light kills nematodes)
Mix nematodes:
- Follow package directions for dilution ratio
- Use unchlorinated water (chlorine kills nematodes; let tap water sit 24 hours)
- Mix gently (don’t use high-pressure sprayer)
- Water temperature 40-90°F
Apply with sprayer:
- Use hose-end sprayer, backpack sprayer, or watering can
- Remove any filters (nematodes clog fine mesh)
- Spray evenly across affected areas
- Keep mixture agitated (nematodes settle quickly)
- Apply 50 million nematodes per 1,000-1,500 sq ft
Water in immediately:
- Irrigate with 1/2 inch water immediately after application
- Nematodes must reach soil (can’t survive on grass blades)
- Keep soil moist for 2 weeks after application
- Light watering daily helps nematodes move through soil

Pros:

Completely safe for people, pets, and beneficial insects
No chemical residue
Can be used on edible gardens nearby
Self-replicating (some nematodes persist year to year)

Cons:

More expensive than chemical treatments ($50-100 for 5,000 sq ft)
Requires precise timing and soil conditions
Less effective than chemicals on heavy infestations
Must be applied correctly (many failures due to improper application)
Short shelf life (must use fresh)

Method 2: Milky Spore (Long-Term Biological Control)

A naturally occurring soil bacterium that specifically targets Japanese beetle grubs.

What is milky spore?:

Paenibacillus popilliae (formerly Bacillus popilliae)
Bacterial disease fatal only to Japanese beetle grubs
Grub ingests spores while feeding
Bacteria multiply in grub’s blood, turn it milky white
Grub dies; body releases millions more spores into soil
Spores persist for 15-20 years once established

Effectiveness:

Japanese beetle grubs only: 75-95% control (highly specific)
No effect on: June bugs, chafers, or other grub species
Takes 1-3 years to establish fully
Provides long-term suppression (decades)

When to apply:

Best timing: Late summer through fall (August-November)
Can apply spring or early summer if needed
Soil temperature above 65°F (bacteria won’t establish in cold soil)
Grubs must be actively feeding

How to apply milky spore:

Determine application method:
- Powder form: St. Gabriel Organics Milky Spore (most common)
- Granular form: Some brands offer spreader-ready granules
Powder application (traditional method):
- Apply 1 teaspoon per spot in grid pattern
- Space spots 4 feet apart in all directions
- Covers about 2,500-3,000 sq ft per 10 oz container
- Use drop spreader or apply by hand
Grid pattern layout:
- Mark lawn in 4 ft x 4 ft grid
- Drop 1 teaspoon powder at each intersection
- Water in lightly (1/4 inch irrigation)
- Powder washes into soil and establishes
Watering requirements:
- Water immediately after application
- Keep soil moist for 2-3 weeks
- Requires moisture to activate bacteria
Repeat applications (optional but recommended):
- Apply second treatment 3 months after first
- Third application 3 months later
- Increases speed of establishment

Pros:

Lasts 15-20+ years once established
Completely safe for all non-target organisms
No reapplication needed after establishment
No mixing or equipment required
Can be applied any time during growing season

Cons:

Only works on Japanese beetle grubs (useless for other species)
Slow to establish (1-3 years for full effect)
Expensive upfront ($40-80 per 5,000 sq ft)
Doesn’t work in cold climates (requires soil temp 65°F+)
Must have Japanese beetle grubs present to establish
Not effective for immediate control

Method 3: Chemical Grub Control (Fast-Acting Treatment)

Synthetic insecticides provide rapid knockdown of heavy infestations.

Active ingredients and products:

Curative treatments (kill existing grubs):

Trichlorfon (Dylox):

Speed: Kills grubs in 24-48 hours
Best for: Emergency treatment of severe damage
When to apply: August-October when damage visible
Effectiveness: 90-95% control of all grub species
Reapplication: Can reapply after 3 weeks if needed
Safety: Moderate toxicity; keep pets off 24 hours

Carbaryl (Sevin):

Speed: Kills in 3-7 days
Best for: Late-season treatment
When to apply: Late summer through fall
Effectiveness: 75-85% control
Reapplication: Can reapply after 7-10 days
Safety: Higher toxicity to bees; apply in evening

Preventive treatments (kill newly hatched grubs):

Imidacloprid (Merit, GrubEx):

Speed: Systemic; provides season-long control
Best for: Preventing damage in lawns with grub history
When to apply: Late spring to early summer (May-July)
Effectiveness: 90-95% control if applied before eggs hatch
Duration: 3-4 months of protection
Safety: Low toxicity once watered in

Clothianidin (Arena):

Speed: Slow-acting systemic
Best for: Preventing Japanese beetle and June bug grubs
When to apply: Spring or early summer
Effectiveness: 85-95% control
Duration: Full season protection
Safety: Low toxicity after watering

Chlorantraniliprole (Acelepryn):

Speed: Reduced-risk chemical with long residual
Best for: Turf managers; professional-grade product
When to apply: Spring through midsummer
Effectiveness: 90-100% control of all grub species
Duration: 4-6 months
Safety: Very low toxicity; safe around water

Application instructions:

Choose correct product:
- Curative (Dylox, Sevin): Use when damage is visible now
- Preventive (imidacloprid, clothianidin): Use before eggs hatch
Calibrate spreader:
- Use drop spreader or rotary spreader
- Follow product label for spreader settings
- Most products applied at 2-4 lbs per 1,000 sq ft
Apply evenly:
- Mow lawn first
- Apply in two directions (half rate each way for even coverage)
- Overlap slightly to avoid streaks
Water in immediately:
- Irrigate with 1/4 to 1/2 inch water right after application
- Essential for moving insecticide into root zone
- Grubs must ingest treated soil/roots to die
Safety precautions:
- Keep children and pets off treated area until dry
- Don’t apply before heavy rain (prevents runoff)
- Avoid contaminating waterways
- Wear gloves during application
- Store products in original containers

Pros:

Fast, reliable control (especially curative treatments)
Works on all grub species
Cost-effective ($20-40 per 5,000 sq ft)
Widely available at garden centers
Easy to apply with standard spreader

Cons:

Toxic to bees and aquatic organisms
Environmental concerns (especially neonicotinoids)
Kills beneficial soil insects
Potential groundwater contamination
Annual reapplication often needed
Some products banned in certain regions

Method 4: Cultural and Mechanical Controls

Non-chemical practices that reduce grub populations and damage.

Proper lawn care practices:

Healthy, vigorous turf resists grub damage:

Fertilize appropriately: 3-4 lbs nitrogen per 1,000 sq ft annually (makes grass more resilient)
Mow at proper height: 3-4 inches for cool-season grasses (deeper roots tolerate grub feeding)
Water deeply, infrequently: Encourages deep roots that survive moderate grub feeding
Overseed thin areas: Thick turf crowds out beetle egg-laying sites
Aerate compacted soil: Improves root growth and water penetration

Withhold irrigation in summer (strategic approach):

Adult beetles prefer laying eggs in moist, irrigated lawns
Reducing irrigation in July-August makes lawn less attractive
Newly hatched grubs need moist soil to survive
Drought-stressed conditions kill many young grubs
Caution: Only practical in regions where some drought tolerance is acceptable

Biological and mechanical controls:

Encourage natural predators:

Birds: Robins, starlings, crows feed heavily on grubs
- Install bird feeders and baths
- Allow birds to forage on lawn (they indicate grub presence)
Beneficial insects: Ground beetles, rove beetles eat grub eggs and small larvae
- Maintain mulched bed borders (beetle habitat)
- Reduce pesticide use
Parasitic wasps: Tiphia wasps parasitize Japanese beetle grubs
- Plant flowering ground covers (wasp nectar sources)

Physical removal (for small areas):

Dig up affected turf sections
Hand-pick visible grubs from soil
Destroy grubs (drop in soapy water)
Replace turf or reseed
Only practical: For small gardens, flower beds, or spot damage

Row covers and barriers:

Cover vulnerable turf areas with landscape fabric in June-July (prevents egg-laying)
Not practical for large lawns but works for small areas

Landscape choices:

Plant less attractive grass species:

Tall fescue: Coarser texture; less preferred by beetles
Fine fescue: Tolerates shade; less beetle activity in shade
Perennial ryegrass: Recovers quickly from moderate grub damage
Avoid: Kentucky bluegrass in grub-prone areas (highly attractive to beetles)

Replace lawn with alternatives (grub-prone sites):

Ground covers (clover, thyme, sedum)
Mulched beds
Hardscaping (patios, gravel)
Native plants requiring no irrigation

Timing considerations for reseeding:

Fall overseeding: Best time in grub-prone lawns (grubs moving deep for winter)
Spring seeding: Risky if grubs still present (wait until after treatment)

Integrated Grub Management Strategy

Combine methods for best long-term control.

Year 1 (Immediate control):

Late summer: Confirm grub presence (dig test squares)
If 10+ grubs/sq ft: Apply curative chemical (Dylox) for fast knockdown
If 5-9 grubs/sq ft: Apply beneficial nematodes
Repair damage: Overseed bare patches in fall

Year 2 (Transition to biological):

Early summer: Apply milky spore powder (if Japanese beetles confirmed)
Mid-summer: Monitor for adult beetles; note egg-laying activity
Late summer: Apply beneficial nematodes as preventive measure
Fall: Aerate and overseed to thicken turf

Year 3+ (Maintenance):

Spring: Monitor for grub damage from overwintering larvae
Summer: Continue milky spore establishment (reapply if needed)
Fall: Check grub populations (should be declining)
Ongoing: Maintain healthy turf with proper fertilization and mowing

Decision matrix:

Grub Count	Grass Damage	Recommended Action
0-4 per sq ft	None	No treatment needed
5-9 per sq ft	Minimal	Beneficial nematodes
10-14 per sq ft	Moderate	Chemical curative or nematodes
15+ per sq ft	Severe	Chemical curative (Dylox) immediately

Preventing Future Grub Damage

Proactive measures reduce recurring infestations.

Adult beetle control:

Hand-pick beetles: Remove Japanese beetles from roses, grapes, other host plants daily
Beetle traps: Controversial (may attract more beetles than they kill)
- If used, place traps 100+ feet away from lawn
- Empty daily
- Use pheromone lures sparingly
Spray adults: Treat ornamental plants with insecticides to kill egg-laying females (reduces lawn grub populations)

Reduce egg-laying habitat:

Delay irrigation: Don’t water lawn in June-July (beetles prefer moist soil for eggs)
Choose drought-tolerant grasses: Beetles avoid dry lawns
Eliminate beetle food sources: Japanese beetles feed on 300+ plant species
- Remove or net particularly attractive plants (roses, grapes, linden trees)
- Reduces adult beetle populations in your yard

Monitor yearly:

June-July: Watch for adult beetles emerging
August-September: Check for grubs (dig test squares)
October: Confirm success of treatments
April-May: Check for spring grub activity before pupation

Regional considerations:

Northern states: One generation per year; treat late summer only
Southern states: Two generations possible; treat late spring and fall
Coastal areas: June bugs more common than Japanese beetles

Neighborhood collaboration:

Grub control most effective when entire neighborhood treats
Adult beetles fly 1-5 miles from emergence sites
Coordinate with neighbors for area-wide suppression

For more information on lawn health and maintenance, see our lawn care basics guide.

The Bottom Line

Grub worms cause extensive lawn damage by feeding on grass roots, but effective control options exist for every situation and preference. For organic control, apply beneficial nematodes (Heterorhabditis bacteriophora) in late summer when grubs are small and actively feeding — this provides 80-90% control of Japanese beetle grubs with no chemical residue. For long-term suppression of Japanese beetles specifically, milky spore establishes a permanent population of grub-killing bacteria that persists for 15-20 years.

Chemical treatments offer faster results: curative products like Dylox kill existing grubs within 24-48 hours when damage is already visible, while preventive treatments like imidacloprid applied in early summer stop newly hatched grubs before they cause damage. The best strategy combines methods: treat heavy infestations chemically for immediate relief, then transition to biological controls for sustainable long-term management.

Confirm grub populations before treating by digging 1-foot square test sections — 10 or more grubs per square foot requires treatment, while fewer than 5 grubs rarely cause visible damage. Healthy, well-maintained turf with proper fertilization, deep watering, and 3-4 inch mowing height tolerates moderate grub populations better than stressed lawns. For comprehensive pest management strategies, see our common garden pests guide.