Signs of Grubs in Your Lawn: How to Spot an Infestation

Key Takeaways:

• Knowing the signs of grubs in grass helps you catch damage before it spreads across the lawn.
• A simple square-foot dig test confirms whether grubs are the real problem or just a lookalike.
• Grub damage peaks from late summer into fall, with a smaller wave in spring.
• A healthy lawn tolerates a few grubs. Treatment matters only once counts climb high enough to cause visible damage.

Irregular brown patches, spongy turf, and grass that peels back like carpet are all common signs of grubs in your lawn. Grubs are beetle larvae that live in the soil and feed on grass roots, cutting off your turf's ability to absorb water and nutrients. 

By the time the damage shows on the surface, the larvae have often been feeding underground for weeks. Learning to identify the warning signs and verify the cause early can help you protect your lawn and choose the right treatment.

Grubs vs. Other Common Lawn Problems

Several lawn problems can cause brown or stressed grass. These signs can help explain what may be different about grub damage, but a professional evaluation is needed to confirm the cause.

What Are Grubs in the Lawn

Lawn grubs are C-shaped, cream-colored larvae of scarab beetles that live in the soil and feed on grass roots. Common white grubs include masked chafers and May and June beetles, while billbugs are a separate root-feeding pest with a different larval form. Grubs typically live 1 to 3 inches below the soil and can damage roots, causing brown patches and loose turf.

Grub damage can resemble drought, lawn disease, or pet urine, so identifying the cause is important before treatment is recommended.

Common Signs of Grubs in Lawn

Common signs of lawn grubs include brown patches, loose turf, a spongy lawn, and animal digging. Here's what to look for.

1. Irregular Brown Patches That Don't Respond to Watering

Grub damage rarely shows up in neat lines or circles. Instead, you'll see irregular brown areas that spread over time, often starting in the sunniest, driest parts of the lawn. Unlike drought stress, these patches don't green up when you add more water, because the roots feeding the grass have already been severed.

Professional Check: During an evaluation, technicians can assess whether persistent brown patches are related to root damage rather than watering problems.

2. Spongy, Loose Turf

When grubs chew through the roots that anchor your grass, the turf loses its grip on the soil. Walk across an affected area, and it may feel soft or bouncy underfoot, similar to stepping on a thin mat. This spongy feel is one of the clearest signs of lawn grubs.

Professional Check: Technicians can compare affected and healthy areas to assess changes in turf firmness and root support.

3. Grass That Peels Back Like Carpet

This is one of the clearest signs of root damage. When grubs consume the roots that anchor grass, affected turf can become loose and lift away from the soil more easily than healthy turf.

Professional Check: Technicians can inspect the affected turf and root zone to determine whether grub activity is responsible for the damage.

4. Increased Digging by Birds, Skunks, or Raccoons

Birds pecking at the lawn, or skunks and raccoons tearing up sections overnight, aren't random. These animals are digging for a protein-rich meal. Sudden nighttime damage to your turf often means something worth the effort is living just below the surface.

Expert Tip: A rise in animal activity paired with brown patches is a stronger signal than either sign on its own.

5. Wilting Despite Regular Watering

If a section stays wilted and stressed despite regular watering, damaged roots may be the cause. Grubs can eat the roots that help grass absorb water, making the damage look similar to drought stress.

Professional Check: Persistent wilting may require a closer inspection of the soil and root zone to determine whether grubs or another issue is responsible.

6. Visible Grubs in the Soil

The most definitive confirmation comes from finding grubs in the soil. During a professional evaluation, technicians can inspect the root zone and soil beneath damaged areas to confirm whether grubs are present and assess their activity level.

Professional Check: Multiple areas may be evaluated because grub activity can vary across the lawn.

When Grub Damage Is Most Noticeable (Seasonwise)

Grub damage follows a predictable seasonal cycle. Knowing when grubs are most active can help you distinguish their damage from drought, heat stress, or lawn disease 

• Late Summer to Early Fall (August–September): This is when grub damage is most severe. Young grubs feed aggressively on grass roots, causing brown patches, spongy turf, and grass that lifts like a loose carpet. Birds, skunks, and other animals may also dig up the lawn searching for grubs.
• Late Fall to Winter: As temperatures drop, grubs move deeper into the soil and stop feeding. New damage slows, but the brown, weakened patches remain visible.
• Early Spring (March–May): Overwintered grubs return closer to the surface and feed briefly before developing into adult beetles. Damage is usually lighter because cool-season grass grows quickly and can mask minor root loss. 
• Late Spring to Early Summer: Adult beetles emerge and lay eggs in the soil. Lawns often appear healthy during this period, making it the best time to apply preventive grub treatments before the next generation begins feeding. 

What to Do If You Find Grubs in Your Lawn

If your lawn shows several signs of grub activity, the first step is to confirm the cause before treatment is recommended. A few grubs can be present without causing visible damage, so the condition of the turf and level of grub activity both matter.

• Look for the warning signs. Irregular brown patches, loose turf, wilting, spongy areas, and increased animal digging can all indicate possible grub activity.
• Consider the season. Grub damage is often most noticeable from late summer into early fall, although some activity can occur in spring.
• Have the lawn evaluated. A professional inspection can confirm whether grubs are causing the damage and assess the level of activity before treatment is recommended.
• Use the right treatment approach. Grub control should be based on the type and stage of grub activity and the condition of the lawn.
• Support lawn recovery. Once the grub problem is addressed, appropriate watering, fertilization, and overseeding when needed can help the lawn rebuild damaged turf.

Also Read: How to Check for and Get Rid of Spider Mites

Get Professional Grub Control from Stewart's Lawn Care

Stewart's Lawn Care has helped Utah homeowners grow healthier lawns since 1972. Our comprehensive Lawn Care Service includes professional Grub Control to protect turf from damaging white grubs and support healthier roots.

Here's why homeowners choose Stewart's:

• Preventative Grub Protection that helps stop grub damage before it starts, with curative spot treatments for turf insects when needed.
• Targeted grub control treatments to eliminate active infestations and protect your lawn's root system.
• Lawn care program tailored to Utah's climate, delivering healthy, resilient turf throughout the growing season.
• Unlimited free service calls whenever your lawn needs additional attention.

If you notice signs of grubs, contact Stewart’s today. Inspect your lawn, confirm the cause, and get the right recommendation for Grub Control treatment.

Frequently Asked Questions

What are grubs?

Grubs are the larvae of scarab beetles such as June beetles and masked chafers. They are C-shaped, cream-colored larvae that live in the soil and feed on grass roots.

What are the first signs of grubs in a lawn?

The first signs of grubs can include wilting or dying grass, a spongy feel underfoot, loose turf, and irregular brown patches.

What does grub damage look like?

Grub damage often appears as irregular brown, thinning, or dead patches. As grubs feed on the roots, affected turf can become loose and lift away from the soil.

How can I tell if I have grubs or lawn fungus?

Grub damage can cause loose turf and root damage, while lawn diseases can cause discolored or thinning grass without affecting how firmly the turf is rooted. A professional evaluation can help confirm the cause.

What time of year do grub problems appear?

Grub problems are most noticeable from late summer through early fall, when young grubs actively feed on grass roots. Some damage can also occur in early spring as overwintered grubs resume feeding.

Can grass recover after grub damage?

Yes. Grass can recover if grub damage is addressed early and enough healthy roots remain. Severely damaged areas may need reseeding or new sod.

Should every lawn with grubs be treated?

No. A few grubs may be present without causing noticeable lawn damage. Treatment depends on the level of grub activity, visible root damage, and the overall condition of the lawn.