sustainability through science & innovation

Pasture day moth caterpillars

Agronomist, Andrew Reardon (JJS Glass & Co), reported observing high numbers of caterpillars within two barley paddocks near Junee, in the South West Slopes district of New South Wales. The caterpillars have been found primarily feeding on wireweed interspersed within the paddocks. They have been identified as pasture day moth (Apina callisto) caterpillars. Andrew says they have not caused any damage to the barley plants, which are at the early tillering stage. Both paddocks contain reasonably high densities of weeds, and have also recently experienced some issues with cutworms causing plant loss.

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, which become more apparent as they mature in size. When viewed closely, they are noticeably hairy, with prominent bristles.

The adult moths are brown with yellow markings on the wings and orange on the body. They fly in autumn and, as the 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 may be seen burrowing in 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.

The pasture day moth is a sporadic pest, and has not been a significant issue for several years in south-eastern Australia. The last substantial outbreak in New South Wales was in 2007 where pasture day moth were reported across much of southern NSW, mostly attacking cereals and emerging pastures.

Pasture day moth caterpillars have a preference to feed on broadleaved weeds and will often leave cereals and grasses untouched where they have a choice in pastures. However, in paddocks where caterpillars are present and broad-leafed weeds are dead or dying from a previous herbicide spray, the grubs will transfer off the dying host plants and onto nearby cereals or grasses. If chemical control is required, alpha-cypermethrin is reported to provide good control of pasture day moth caterpillars.

PestFacts is supported by