Pasture day moth

Agronomist, Peter Watt (Elders), reports pasture day moth grubs in a paddock near Harden, in the South West Slopes of NSW. They are reported to be causing visible chewing damage to wheat seedlings at the 1-2 leaf stage. Peter says the grubs are between 20-30 mm long and present in high numbers, with several caterpillars observed per square metre. Due to the level of damage, the paddock will be sprayed using a synthetic pyrethroid.

Pasture day moth (Apina callisto) 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. Pasture day moths are found in most southern areas of Australia, ranging from lower Queensland to Tasmania.

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 passes through only one generation per year.

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 cereals.

It is important to correctly identify caterpillars as an assortment of species may be present including brown pasture looper and pasture web worm.