Turfmate field notes · Pests

Lawn armyworm

Spodoptera mauritia

Fast-moving leaf damage: inspect for caterpillars, not just moths.

Adult lawn armyworm moth. The caterpillar stage, rather than this adult, feeds on grass.
Adult lawn armyworm moth. The caterpillar stage, rather than this adult, feeds on grass.
Photo: Richard Fuller · source · CC0. Displayed at reduced size; card crops fit the layout.

What to look for

  • Leaves are chewed or stripped, sometimes across an advancing patch.
  • Caterpillars may hide in the thatch during the day.
  • Fresh feeding is easier to find near dusk or after dark.

Confirm it before you treat it

Armyworm, cutworm and other lawn caterpillars need a close look to separate them. Photograph the caterpillar and the damage together. The adult moth image in this guide shows another life stage; moths themselves are not eating your lawn.

What to do next

  1. Inspect the edge of fresh damage promptly and confirm active caterpillars.
  2. Record how quickly the patch is changing and whether leaves or roots are being lost.
  3. Ask for help if damage is accelerating; treatment should match the species, stage and site.
Seasonal watch

Conditions matter more than dates.

Warm growing periods provide a useful monitoring window. Local moth activity and actual caterpillar feeding are better triggers than a date alone.

Monitor through spring, summer and autumn in southern lawns; warm northern sites may need checks over a longer season.

Explore your region & month ↗

Are moths proof of an attack?

No. A moth sighting is a reason to look closely, but confirm caterpillars and fresh feeding before choosing a treatment.

Inspect & compare

More views. Better clues.

Read each caption and compare fresh symptoms in your own turf.

Black cutworm larva, pictured on soil beside a corn seedling.
Black cutworm larva, pictured on soil beside a corn seedling.
Photo: W. M. Hantsbarger, Bugwood.org · source · CC BY 3.0 US. Displayed at reduced size; card crops fit the layout.
Keep investigating

Similar problems. Different solutions.

Reviewed 11 October 2026 · Turfmate. Seasonal windows are indicative planning guidance, not measured outbreak or prevalence data.

Technical sources & image credits

Photos support identification and may have been taken outside Australia. Appearance varies with species, mowing and conditions. A Turfmate product link does not imply endorsement by a photographer or source.