Lawn grubs (curl grubs)
Heteronychus arator and other scarab larvae
C-shaped, cream-coloured beetle larvae that live in the soil and eat grass roots. Damaged patches turn brown and lift easily because the roots are gone.
Also called: Curl grubs, African black beetle, Black beetle, White grubs
Short answer
Lawn grubs, or curl grubs, are C-shaped, cream-coloured beetle larvae that live in the soil and eat grass roots. Damaged patches turn brown and lift like carpet. Lift a section of turf at the edge of a brown patch to look for them. If you find enough to explain the damage, treat with a product whose label lists them and your grass.
Overview
“Lawn grubs” usually means curl grubs: the larvae of African black beetle and other scarab beetles. They live in the soil and feed on grass roots. The first you see of them is usually a brown patch that doesn’t respond to watering.
Because dry patches look similar, always confirm grubs before treating. Lift a piece of turf at the edge of a damaged area and look in the root zone. If you find C-shaped, cream grubs, you know what you’re dealing with.
The activity months shown are a general guide from an industry identification guide (early spring to mid summer for African black beetle larvae). Timing varies with the season and the species.
Signs of damage
- Brown or dead patches that keep spreading, even with watering
- Turf that lifts easily at the edge of a patch, because the roots have been eaten
- C-shaped, cream grubs with brown heads in the top few centimetres of soil
- Birds digging and pecking at the lawn more than usual
How to check
At the edge of a brown patch, where grass is still partly green, cut and lift a spade-sized piece of turf.
Look in the root zone and top few centimetres of soil for C-shaped, cream grubs with brown heads.
Check a few spots, including healthy-looking lawn nearby, to see how widespread they are.
When it's active
| Zone | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Subtropical | ● | ● | ● | ● | ● | |||||||
| Warm temperate | ● | ● | ● | ● | ● | |||||||
| Temperate | ● | ● | ● | ● | ● |
What favours it
- Warm months, when larvae are feeding
- Lawns already under stress from dry or compacted soil
Control without chemicals first
Water and feed a damaged lawn so the grass can regrow roots once the grubs are dealt with.
Fix dry patches and compaction so the lawn is less stressed.
Treatment options
| Timing | Active ingredient | What it does | Grass types |
|---|---|---|---|
| curative | See product label | Insecticides registered for lawn grubs. Choose one whose label lists the pest and your situation. Several lawn insecticides carry label warnings about bees and aquatic life, so follow the label exactly. | Check the label |
In the Lawn Calendar
Look for brown patches where the turf lifts like carpet, and birds digging in the lawn. Lift a section of turf at the edge of a patch and check for C-shaped, creamy white grubs in the root zone.
January, September, October, November, December · Subtropical, Warm temperate, Temperate
Popular questions about lawn grubs (curl grubs)
Guides
Common questions
Are the black beetles on my path the problem?
The adult beetles chew stems, but most lawn damage comes from the larvae (grubs) eating roots under the surface. Check the soil under a brown patch.
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Who wrote this, and what it's based on
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Sources
- Turf weed, pest and disease identification guide (poster), Bayer Environmental Science, hosted by Turf AustraliaAfrican black beetle larvae occur from early spring to mid summer and damage turf roots. Accessed 3 October 2026.
- Scarabs, Business Queensland, Queensland GovernmentScarab beetle larvae (curl grubs). Accessed 4 October 2026.