White grubs are the larvae of chafer beetles and Japanese beetles. They eat grass roots, so the lawn yellows and lifts like a carpet. Skunks and raccoons often dig it up to eat them. The most common treatment in Quebec, beneficial nematodes, is applied from mid-August to mid-September on soil at least 12°C, kept moist for 7 to 15 days afterwards.
Signs of an infestation
- Yellow then brown patches that don’t recover after watering
- Turf that lifts easily like a carpet, with no roots
- Lawn torn up by skunks, raccoons or birds
- Lots of beetles around lights in early summer
The simple test
Cut three sides of a 30 cm square of turf, 5 cm deep, and lift it. Several white C-shaped larvae in that square mean a significant infestation. Repeat in a few spots.
Treatment
- Beneficial nematodes: microscopic worms that parasitize the larvae, applied by watering, mid-August to mid-September.
- Approved products: some low-impact insecticides exist, but their use is regulated in Quebec and Montreal. See pesticide rules.
- A healthy lawn: dense, mowed high and well fed, it resists better.
After control, rake dead areas, top-dress and overseed. Don’t confuse with chinch bugs.
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General information. Pesticide use is regulated in Quebec and by many municipalities.