On the radar: Common armyworm

We have received report of common armyworm activity in barley crops in the Eyre Peninsula.

Armyworm larvae are common pests of pastures, cereals, and rice. They can damage cereals during autumn and winter and may feed on cereal heads in maturing crops. Severe infestations can lop barley heads, while wheat, with its thicker stems, is less affected.

Identifying armyworm

There are 3 common armyworm species in southern Australia (other regions have different species):

• Southern and inland armyworms (Persectania spp) are typically found during autumn and winter, but their activity can sometimes spread into spring.
• Common armyworm (Leucania convecta) can be seen year-round, but particularly in spring.

Armyworm larvae start at approximately 1 mm after hatching and can grow up to 40 mm in length. They are identifiable by 3 parallel white stripes along their smooth, slightly hairy bodies. Larvae typically feed on and cause damage to crops. In extreme cases of food scarcity, they may 'march' in large groups to find new sources of food.

The adult moths are grey-brown and have a stout body with a wingspan of about 40 to 45 mm.

Armyworm caterpillars can be confused with:

• native budworm, which has more prominent body hairs
• cutworms, which have absent or indistinct stripes
• herringbone caterpillars, which have herringbone-like markings on the stripes down the body.

The exotic fall armyworm (FAW, Spodoptera frugiperda) is not present in SA but looks similar to other native armyworms with the typical 3 stripes. If you suspect a caterpillar is FAW, please contact the Emergency Plant Pest Hotline on 1800 084 881 or submit a plant pest report.

Common armyworm on barley (photo by C. DuBois)