Pasture day moth

Pasture day moth larvae have been detected in various pasture paddocks around Charlton, in the Wimmera district of Victoria. Consultant, Tom Lord (AGRIvision Consultants), reports finding larvae more commonly in paddocks which have some capeweed present, and says they do not appear to be damaging lucerne or cereal crops at this stage. Early instar pasture day moth larvae have also been identified for agronomist, Louisa Ferrier (John Stuchbery & Associates), from a pasture paddock near Beaufort, in the Western district of Victoria. Louisa reports finding some damage on the clover, however it is not clear at this stage whether this is due to these grubs or whether something else is also present.

Pasture day moth (Apina calisto) 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. 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. 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.

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 plants. If chemical control is required, alpha-cypermethrin is reported to provide good control of pasture day moth caterpillars.