The Porina caterpillar causes similar damage to lawn grass and pastures as grass grub, causing bare patches and an increased incidence of flat weeds. However, it tends to feed on leaves rather than the roots. The caterpillars are greyish yellow with a dark brown head and grow up to 6cm in length.
The adult Porina moth is a fat brown moth that flies around your lights at night. It lays 100+ eggs on grass in spring and summer. On hatching the caterpillars move to leaf bases where they feed. As they grow, they burrow into the soil and emerge at night to feed on the leaves. They do most damage in Autumn and early winter.