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Grub Control in Peoria, IL
White grubs, the larvae of Japanese beetles and masked chafers, eat grass roots in late summer. The lawn turns brown in patches and peels up like loose carpet. Here’s how to tell if it’s grubs and when treatment actually works.
Signs of grubs
- Brown patches in late August–September
- Turf lifts up like carpet
- Skunks, raccoons or birds digging
- C-shaped white larvae in the soil
- Damage that doesn’t green up with water
Short answer
How do I know if I have grubs?
Pull back a square foot of brown turf at the edge of a dead patch. If it lifts easily and you see C-shaped, cream-colored larvae with brown heads in the top inch or two of soil, it’s grubs. A handful per square foot usually isn’t worth treating; around 10 or more usually is.
Is it grubs or just drought? Drought-stressed grass is still rooted. Grub-damaged grass pulls up with almost no roots. Animals digging at night is another strong clue.
Look-alikes
Grubs vs. other brown patches
| Cause | What you see | Tug test |
|---|---|---|
| Grubs | Irregular brown patches late Aug–Oct; animals digging | Lifts easily, no roots |
| Drought | Lawn-wide tan or straw color, worst in sun and slopes | Firmly rooted; greens up with rain |
| Lawn disease | Circular or irregular spots, often in humid weather | Rooted; leaf blades show lesions |
| Dog spots | Small round dead spots with a green ring | Rooted |
Life cycle
The grub year in central Illinois
- Early to mid summer: Japanese beetles and masked chafers lay eggs in lawns, often in irrigated, green turf.
- Late July to October: Young grubs hatch and feed on roots. Damage shows from late August.
- Winter: Grubs move deeper below the frost line.
- Spring: They come back up and feed briefly before turning into beetles. Damage is usually lighter.
That’s why preventive products go down in June to July, and rescue treatments work best in late August to September when grubs are small and near the surface.
Timing
When to treat grubs in central Illinois
| Approach | When | How it works |
|---|---|---|
| Preventive | June into July | Applied before eggs hatch, so young grubs are controlled as they start feeding. Best for lawns with grub damage in past years. |
| Curative | Late August into September | Used when grubs are already active and damage is showing. Works best on young grubs near the surface. |
| Spring | April–May | Grubs are large and feeding less; treatment is less effective. Usually better to repair and plan prevention. |
Applying grub products needs a licensed applicator when done for hire in Illinois. [Partner to confirm license.]
Repair
Fixing grub-damaged lawn
- Rake out dead turf once grubs are controlled.
- Loosen the soil surface and overseed in early fall, or patch with sod.
- Keep new seed moist until it’s established.
See aeration and overseeding and sod and seeding.
FAQ
Grub control questions
Do I need to treat for grubs every year?
Not always. Lawns with a history of grub damage often benefit from yearly prevention; others can skip it and monitor in late summer.
Why are skunks digging my lawn?
They’re usually hunting grubs. Controlling the grubs usually stops the digging.
Will Japanese beetle traps help?
Traps can attract more beetles to your yard than they catch. They’re not a reliable way to prevent grubs.
Can grub damage happen in spring?
Some damage shows in spring, but late summer is when grubs do most of their feeding in central Illinois.
Related: Lawn care · Fertilization and weed control · Sod and seeding
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