Brown patches, raccoons digging at night, turf that lifts like carpet — Toronto is ground zero for European chafer grubs. Identify, treat and recover from grub damage in your GTA lawn.
Lawn grubs are the white, C-shaped larvae of beetles — primarily the European chafer and June beetle in the GTA. They live 2 to 4 inches below the soil surface, feeding on grass roots from July through September. A healthy lawn can tolerate 3 to 5 grubs per square foot. Above 5 per square foot, you will see visible damage. Above 10 per square foot, the lawn will die in affected patches.
Toronto and the inner GTA are ground zero for European chafer in Canada. The chafer was introduced to the Hamilton area in the 1940s and has since spread east across the GTA. It thrives in the well-irrigated, Kentucky bluegrass-dominant lawns that make up most Toronto and North York residential properties. The beetles emerge in June to lay eggs in turf, the eggs hatch in August, and the larvae feed through September before going dormant for winter — only to resume feeding briefly in spring.
Yes, if you have more than 5 grubs per square foot. Grubs chew through the root zone from July to September, and visible damage — brown patches, loose turf that lifts like carpet, wildlife digging — appears in August and September. Leaving a confirmed infestation untreated means the same patches die again next year as the new generation hatches. Light infestations (under 5 per square foot) with no visible damage can often be monitored rather than treated.
Nematodes target young, near-surface grubs. In spring, surviving grubs have moved deep into the soil (6 to 12 inches) to avoid freeze-thaw, and are too large for nematodes to be effective against. By the time soil warms enough for nematode activity, the grubs have pupated and are preparing to become adult beetles. The window for effective nematode treatment is late August to mid-September, when newly hatched young grubs are 1 to 2 inches below the surface.
Yes. Beneficial nematodes (Heterorhabditis bacteriophora — the Hb strain) are microscopic roundworms that are completely harmless to humans, pets, birds, and earthworms. They only parasitize specific insect larvae. There is no withholding period — kids and pets can use the lawn immediately after nematode application and watering-in.