The potato moth (Gnorimoschema operculella) is present in every potato-growing district in New South Wales and the caterpillars may cause considerable damage to foliage and stems in early summer, particularly in coastal areas, and injure the tops to such a degree that the plants die prematurely, with consequent loss in yield. A much more serious form of injury may be caused to the tubers, both while growing and during storage.

The moths are small, inconspicuous, and may be seen flying actively at dusk whereas they hide away amongst clods and rubbish during the day. Eggs arc laid on the undersurfaces of the leaves and the young caterpillar tunnels into the leaf tissue causing typical blistering. The growing larva tunnels into the leaf stalk and finally into the main stem.

Thelarva leaves the plant and pupates beneath clods or amongst plant refuse on the ground. The full life-cycle occupies four weeks under favourable conditions. Where infestations occur during storage the eggs arc laid in the eyes, scars, cracks or under loose pieces of skin. The young larvae normally enter the tubers through the eyes and breeding may proceed continuously, except in very cold weather, until the potatoes are completely destroyed.