Lawn Armyworm

Spodoptera mauritia

A moth caterpillar that feeds on grass at night and can turn lawns brown within days, especially in Queensland and northern NSW in late summer and autumn.

Written by PestMan Editorial TeamTechnical review pendingPublished 1 September 2026Updated 20 September 2026

Size: Up to about 40 mm
Feeds: At night, on grass blades
Peak: Late summer to autumn
Test: Soapy water flush

Questions about the Lawn Armyworm

How to identify a Lawn Armyworm

Identification

Caterpillars up to about 40 mm, green to brown or grey with pale stripes along the body.
Curl into a C shape when disturbed.
Adult moths are grey-brown and fly at night.

Where it lives

Warm-season lawns, sports fields and pasture.
Hide in the thatch during the day.

Behaviour

Feed at night, eating grass blades down to the stems.
Move across a lawn as a front, leaving brown, straw-like grass behind.

Why it matters

Damage spreads fast, so early detection matters. See how to know if you have armyworm.

Commonly confused with

Curl Grubs

Scarab beetle larvae (Scarabaeidae)

C-shaped, creamy-white beetle larvae that live in soil and eat grass roots, causing patches of turf that die and lift away like loose carpet.

Other lawn pest species

African Black Beetle

Heteronychus arator

An introduced, shiny black scarab beetle whose larvae are a common type of curl grub. Adults also chew grass at the base and are drawn to lights.

Guide

Common Brisbane Household Pests

A Brisbane-specific overview of the pests residents meet most often, when they are active, and what the subtropical climate, storms, creeks and Queenslander homes mean for pest pressure.

Guide

Understanding Pest Activity After Rain

Why storms and wet weather bring cockroaches, ants, mosquitoes and spiders into homes, what to expect in the days and weeks afterwards, and what to do before and after rain and floods.

Common Pests in Brisbane

More about lawn pests

Lawn Pests

Caterpillars and beetle larvae that eat grass leaves or roots, leaving brown, dying patches. Armyworm and curl grubs cause most lawn damage in eastern Australia, especially in warm, humid months.

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Sources & further reading

Queensland Museum — insects, spiders and animals of Queensland — Queensland Museum
CSIRO — insect and pest research — CSIRO

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