What's eating your grass? Identify the lawn pest by damage pattern: brown patches (grubs), chewed blades (armyworms), yellow spreading spots (chinch bugs), or dug-up areas (moles).
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The damage pattern tells you the pest. Irregular brown patches that peel up like carpet: grubs. Ragged chewed grass blades: armyworms or sod webworms. Yellow patches spreading in hot weather: chinch bugs. Tunnels and ridges: moles. Scattered digging holes: skunks or raccoons eating grubs.
Browse all causes below. Each includes symptoms, a photo placeholder, confirmation test, and treatment links.
Pattern: Irregular brown patches that peel up like loose carpet, worst in late summer and fall, spongy turf
C-shaped beetle larvae that feed on grass roots 1 to 3 inches below surface. Grass dies because it has no roots. Worst August through October. A healthy lawn tolerates 5 to 8 per square foot. Above that, treatment is needed.
Cut a 1 sq ft section and peel it back. Count the white C-shaped grubs. More than 8 to 10 per sq ft confirms treatable infestation.
Pattern: Grass blades chewed to stubs overnight, brown patches with ragged edges, green pellets on soil
Caterpillars that feed on blades in large numbers, often stripping an area overnight. Most active late summer and fall. Grass recovers after treatment because roots aren't damaged.
Pour soapy water (2 tbsp soap per gallon) over damaged area. Caterpillars surface within 5 minutes. Check at dusk.
Pattern: Yellow patches spreading outward in hot dry weather, usually in full-sun areas, doesn't respond to watering
Tiny insects (one-eighth inch) that suck grass stem juices and inject a toxin preventing water uptake. Damage looks like drought stress but watering doesn't help. Worst July to August.
Push a bottomless can into soil at patch edge. Fill with water. Chinch bugs (tiny, black, white wing patches) float to surface.
Pattern: Scattered thin patches, grass chewed at base, small tan moths flying low over lawn at dusk
Small caterpillars in silk-lined thatch tunnels that chew blades at the base. Less dramatic than armyworms but persistent. Tan moths at dusk are the adult stage laying eggs.
Part grass in thin area. Look for silk-lined tunnels in thatch and green frass pellets near soil surface.
Pattern: Raised tunnels (moles), scattered 2 to 3 inch holes (skunks), torn-up turf sections
These animals eat grubs, not grass. Moles tunnel following grub populations. Skunks dig holes to find them. Eliminate the grubs and the digging animals leave within 2 to 3 weeks.
Mole tunnels plus brown patches that peel up means grubs. The animals are the symptom, not the cause.
Insects: white grubs eat roots, armyworms eat blades, chinch bugs suck stem juices. Animals: moles, skunks, and raccoons dig up grass to eat grubs but don't eat the grass itself. Rabbits nibble but rarely cause significant damage.
Brown patches that peel up like loose carpet. Cut a 1 sq ft section and pull it back. Count the white C-shaped grubs. More than 8 to 10 per sq ft needs treatment. Damage is worst August through October.
Most likely armyworms or sod webworms. Both are caterpillars active at night. Pour soapy water over a damaged area at dusk: caterpillars surface within minutes. Armyworms cause dramatic overnight damage. Webworms cause gradual thinning.
They're hunting grubs. Treat the grub infestation and digging stops within 2 to 3 weeks as the food source disappears. Trapping the animals doesn't solve the underlying grub problem.
Preventive: June to early July before eggs hatch (imidacloprid, chlorantraniliprole). Curative: August to September for active infestations (trichlorfon, carbaryl). Preventive is more effective and less toxic.
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