Grubs in lawns
Lawn grubs are the larvae of several beetles, and the species matters: thresholds run from 2–4 per ft² for May beetle grubs to 12–20 for Asiatic garden beetle, and milky spore affects only Japanese beetle. Sample in August, when the new grubs are small and near the surface. That is also the window for the nematode, which needs moist soil at 12–30 °C (54–86 °F) for two weeks after it goes on.
At a glance
- Damage
- Grubs chew grass roots; turf browns and lifts like a carpet
- Type
- Root
- Settings
- Garden
- Threshold
- 5–10 grubs per ft², by species; more in irrigated turf
- Release
- Heterorhabditis bacteriophora
- Rate
- About 250k–500k nematodes /m² for Japanese and Oriental beetle grubs (BASF: 25–50 million per 1,000 ft², or 1–2 billion per acre); BASF gives European chafer double that
How to confirm it
Grab a handful of the browning turf and pull. If it lifts like a carpet with few roots, look in the top 1–2 inches (2.5–5 cm) of soil for white, C-shaped larvae with brown heads and six legs.
Identification, lifecycle, degree days and every control option are on the full White grubs profile. Not sure it is this pest? Answer four questions about the damage.
Work it out
How many do I need?
Carries Heterorhabditis bacteriophora and lawn & turf through so nothing is re-entered. Open the calculator →