Exotic southern armyworm and established fall armyworm

PLANT PEST

Exotic southern armyworm and established fall armyworm

Southern armyworm (Spodoptera eridania) is exotic to Australia, while fall armyworm (Spodoptera frugiperda) is now established in Australia

Features: Larva – fall armyworm either light green or brown with white lengthwise lines; southern armyworm grey–brown with reddish lines underneath
Moth – both species look very similar, with brown or grey forewings and white hind wings

Where they’re from: Both fall armyworm and southern armyworm are native to tropical and subtropical regions of the Americas. They are widely distributed in Africa. Fall armyworm is also established in parts of Asia

How they spread: Adults can fly long distances, and they can also be
spread through movement of people

At risk: alfalfa, barley, buckwheat, clover, cotton, maize, millet, peanut, sugarbeet, soybean, sugarcane, tobacco, wheat, apple, grape, orange, papaya, peach, strawberry and a number of flowers, weeds and grasses.

Egg mass of fall armyworm. Ronald Smith, Auburn University, Bugwood.org

Report it

Australian Chief Plant Protection Officer, Dr Gabrielle Vivian-Smith, provides an overview of the fall armyworm (present in Australia).

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Keep it out/stop the spread

It’s everyone’s responsibility to watch out for this destructive pest and protect Australia’s agricultural industries and environment.

Fall armyworm larvae is known to feed on more than 350 plant species, while southern armyworm has been recorded on 200 plant species. Both cause significant economic losses overseas. Larvae are most active during late summer and early autumn months.

The adult moth can fly long distances and its migration rate is remarkably fast. As well as natural dispersal, it can also be spread through movement of people.

Fall armyworm has been detected in the Torres Strait, Queensland, Western Australia, the Northern Territory, New South Wales and Victoria.

Southern armyworm larva (Source: *Richard Sprenkel, University of Florida, Bugwood.org*).

A stripy brown, cream and pink caterpillar on a green leaf. — Leaf miners damage many vegetables including peas. *Whitney Cranshaw, Colorado State University, Bugwood.org*

Importing goods

To keep the exotic southern armyworm out of Australia, never ignore Australia’s strict biosecurity rules.

Import shipments may need to be treated and certified, so before you import, check our Biosecurity Import Conditions system (BICON).

What to look for

Eggs

Pale yellow (fall armyworm) or greenish (southern armyworm) and less than 0.5 mm in size
100–200 eggs in a ‘mass’ laid on underside or top of leaves
Covered in a pale, felt-like layer of scales

Larva (early development)

Fall armyworm:

Light green to dark brown
White lengthwise lines
Dark spots with spines develop as larvae mature
Distinctive pattern of four spots on second-to-last body segment
Inverted ‘Y’ shape pattern on its head.

Southern armyworm:

Young larvae black with yellow lengthwise lines
Older larvae grey-brown with a row of paired black triangular spots along its back, and reddish lines underneath

Moth (adult)

32–40 mm from wing tip to wing tip
Brown or grey forewing
White hind wing
Males have more patterns with a distinct white spot on forewings.

Where to look

Both southern and fall armyworm are likely to be found in warm, moist regions.

In areas with little forest cover
Hitchhiking on fresh vegetables or fruit.

In these areas, look for the following:

egg masses
plant leaf damage
fruit or vegetable damage.

Importers

Keep an eye on all cargo, containers or parcels arriving through airports, seaports and in international mail. If you see something unusual or unexpected on imported plant material, secure it and report it to us immediately.

Growers and home gardeners

Look out for significant and unusually high levels of damage by caterpillars to foliage of:

corn
sugarcane
rice
Sorghum and other grasses.

What to do

Both southern and fall armyworm are likely to be found in warm, moist regions.

do not disturb the material or insect (this may be as simple as closing the doors on a shipping container or covering infested plant material with plastic)
take a photo and collect a sample, if possible, without disturbing them.

Report it

Seen something unusual? Report it. Even if you’re not sure.

Exotic southern armyworm and established fall armyworm