Grub Control Timing and Managing Animal Damage in Michigan Lawns

Understanding the Grub Cycle

Skunks and raccoons tearing up a 10×20 ft lawn area in early spring indicate they are feeding on mature grubs. The homeowner applied Scotts GrubEx early, but the product’s label suggests July application. In Michigan, the optimal window for preventive grub control is late July to early August, targeting newly hatched larvae before they cause significant root damage.

Why Spring Treatment Often Fails

Spring grubs are large, near pupation, and less susceptible to insecticides. They will soon dig deeper, lay eggs, and die. Treating now wastes product and doesn’t stop the next generation. Watering heavily after application helps move chemical into the root zone, but it won’t reverse the timing mismatch.

Integrated Approach

• Monitor: Peel back sod in late summer to check grub density (5–10 per sq ft warrants treatment).
• Preventive application: Apply a product containing imidacloprid (Merit) or chlorantraniliprole in late July.
• Animal deterrents: Blood meal (dried blood) can repel skunks/raccoons; motion‑activated sprinklers or physical barriers also help.
• Repair: Rake damaged areas, overseed with a quality Kentucky bluegrass/perennial ryegrass mix in early fall, and keep moist.

For ongoing vertebrate issues (groundhogs, possums), consult a wildlife control specialist; habitat modification (removing den sites under sheds) is more effective than repellents.