Pasture day moth

Like many establishment pests, this season has favoured the pasture day moth, a dark caterpillar pest with distinctive red-orange markings. Limited cotyledon damage has been observed in canola.

 

Where have they been reported?

Pasture day moth (Apina callisto) larvae have been detected in a canola (cotyledon stage) paddock west of Tocumwal in Victoria’s Northern Country. The distinctive caterpillars have been damaging the cotyledons in various patches across the paddock. A few weeks’ earlier, considerable areas of capeweed had been sprayed out, almost certainly forcing the resident larvae onto the newly emerged canola seedlings.

Pasture day moth habits and behaviour

Pasture day moths fly in autumn and, as their name implies, are active during the day. Eggs are laid in pasture and hatch at the onset of rains. When the larvae are fully grown, they burrow into the soil before becoming pupae. The pasture day moth has only one generation per year and is found in most southern areas of Australia, ranging from lower Queensland to Tasmania. Little is known about natural biocontrol agents.

Our advice

Pasture day moth caterpillars have a preference to feed on broad-leaved weeds and will often leave canola, cereals and grasses untouched where they have a choice. However, in paddocks where broad-leaved weeds are dying from a previous herbicide spray, the grubs will transfer off the dying host plants and onto nearby plants. Monitor crops for the presence of caterpillars, which are usually quite easy to detect feeding on plants during the day. Caterpillars will remain active for several months; the majority of issues previously reported to PestFacts have been from late winter onwards.

Control options

If chemical control is required, alpha-cypermethrin is reported to provide good control of pasture day moth caterpillars. In most instances however, pasture day moth do not reach damaging levels.

Description

Pasture day moth caterpillars are easily identified when they are fully grown by their dark brown to black colour and reddish-orange markings. They grow to about 50-60 mm long and have two prominent yellow spots near their rear end. These become more apparent as they mature in size. When viewed closely, they are noticeably hairy, with prominent bristles. Click here for images of pasture day moth caterpillars. The adult moths are brown with yellow markings on the wings and orange on the body.

 

* Source of field reports of pasture day moths

David Jarrot - Agronomist, IK Caldwell (Victorian Northern Country)