Treating lawn grubs and insect damage

The signs

• Irregular brown patches that do not recover after watering.
• Turf that lifts like a loose carpet because the roots underneath have been eaten.
• Birds, badgers, skunks or raccoons digging up the lawn to get at the larvae.

Brown patches have other causes too, including drought, disease and pet urine, so confirm before you treat.

Confirm and count

At the edge of a damaged patch, where green meets brown, cut three sides of a square about 30 × 30 cm (1 × 1 ft) and fold the turf back. White grubs are C-shaped, cream-colored larvae with a brown head and six legs near the head. As a rough guide, five to ten per square foot (about 50–100 per m²) is enough to damage a lawn; a couple is normal and not worth treating.

When and how to treat

• Treat while the larvae are young and feeding near the surface, usually late summer to early autumn, and again in spring for some species.
• Beneficial nematodes are a biological option: apply them to moist soil that is at least about 12 °C (54 °F), and keep it moist for two weeks.
• Otherwise use a grub control product authorized in your country, following its label for timing and rate.
• Water the area before and after treatment so the product reaches the root zone.

Repairing the damage

Once the grubs are dealt with, rake out the dead grass and reseed. Healthy, deep-rooted grass tolerates more grubs before it shows damage, so keep up regular care.