Fall armyworm in Western Australia

Page last updated: Monday, 5 July 2021 - 9:47am

Please note: This content may be out of date and is currently under review.


The fall armyworm (Spodoptera frugiperda) is a plant pest that can damage a wide variety of crops. The larvae predominantly feed on crops and pastures from the Poaceae (grass) family, in particular maize, but also sorghum, forage grasses, turf grasses, cereals and rice. The pest can also feed on non-grass crops such as cotton, peanuts, vegetables and some fruit crops. Fall armyworm is known for its ability to disperse and migrate long distances, which enables it to exploit new habitats and expand its range. 

The Department of Primary Industries and Regional Development (DPIRD) is conducting surveillance on the spread of fall armyworm across north Western Australia. Early detection and reporting of fall armyworm will help protect the State’s plant industries and the environment.

Fall armyworm have four life stages: eggs, larvae (caterpillar), pupae and adult (moth). 

Identifying fall armyworm from the eggs, pupae and adult moths is very difficult. The larvae have key identification features growers can use, however many larvae present in Western Australian crops look similar to fall armyworm.  

For a detailed look at the identification characteristics of fall armyworm, watch the webinar conference presentation or read the PowerPoint presentation by DPIRD senior laboratory scientist Melinda Moir, delivered on 9 April 2020 to growers, agronomists and stakeholders.


Fall armyworm eggs are pale yellow coloured and laid as an egg mass, which often contains 100–200 eggs. Egg masses are laid on leaves and covered with a layer of hairs and scales shed by the female moth.

Fall armyworm egg mass on maize
Fall armyworm egg mass.


The appearance of larvae changes as they develop through the life cycle. When larvae first hatch from the eggs, they are light coloured with a larger dark head. 

Fall armyworm larvae
Neonate or newly hatched larvae are light coloured with a dark head.

As they develop, the body of fall armyworm larvae become darker with white lengthwise stripes. They also develop dark spots with spines. The colour can vary from light green to a dark brown and black. 

Top view of young fall armyworm larvae
Top view of young fall armyworm larvae, sized from 6-9mm. Source: Training Manual on Fall Armyworm, Food and Agriculture Organisation of the United Nations. 
Top view of mature fall armyworm larvae
Top view of mature fall armyworm larvae, sized from 30-36mm. Source: Training Manual on Fall Armyworm, Food and Agriculture Organisation of the United Nations. 

Key features found on larvae can be used for identification. For more details, see the Fall armyworm larval identification guide.

Fall armyworm larvae highlighting key identification features
Fall armyworm larvae have key identification features, including four large spots in a square arrangement on the second last segment.


Identification of fall armyworm moths is very difficult and requires an expert. There are many other species of moths that look similar to fall armyworm. 

The adult moths are 32-40mm in length from wing tip to wing tip, with a brown or grey forewing and a white hind wing. Male fall armyworm moths have more patterns on their wings than the females.  Males also have a distinct white spot on each of their forewings.

Male fall armyworm moth
Male fall armyworm moth.
Female fall armyworm moth
Female fall armyworm moth.

What else could it be?

Table A lists pest moths in the crop that could be confused with fall armyworm (as at 20 May 2020)

Common name

Species name

Crops in which it is found

Cluster caterpillar, tobacco cutworm

Spodoptera litura

Cotton, maize, sorghum, pastures, hay

Beet armyworm

Spodoptera exigua

Beets, asparagus, beans, peas, cabbage, pepper, tomato, lettuce, celery, strawberry, eggplant, sugar beet, alfalfa, cole crops, potato, cotton, cereals, oilseeds, tobacco, flowers and weed species

African armyworm

Spodoptera exempta

Cereals, maize, rice, sorghum, sugarcane, and pasture grasses, especially Cynodon and Pennisetum species

Native budworm

Helicoverpa punctigera

Maize, cotton, canola, pulses, sunflower, flax, pasture legumes, fruit and vegetable crops

Corn earworm, cotton bollworm

Helicoverpa armigera

Major hosts: maize, tomato, cotton, pigeon pea, chickpea, rice, sorghum, and cowpea. Other hosts include: groundnut, okra, peas, field beans, soybeans, lucerne, Phaseolus spp., other Leguminosae, tobacco, potatoes and flax

Lesser budworm

Heliothis punctifera

Cereals and lucerne

Northern armyworm

Mythimna separata

Rice, maize, sorghum, wheat, sugarcane and wild grasses

Common armyworm

Mythimna convecta

Poaceae spp. (inc. cereals and grasses), pineapple, sweet potato and lucerne

Sugarcane armyworm

Mythimna loreyimima

Sugarcane, Poaceae spp. (inc. cereals and grasses)

Southern armyworm

Persectania ewingii 

Poaceae spp. (inc. cereals and grasses), peas and flax

Inland armyworm

Persectania dyscrita

Poaceae (inc. cereals and grasses)

Black cutworm

Agrotis ipsilon

Maize, crops and weeds


Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080