Ian Roger, of Otago, asks :-

In tussock and snow grass of the hills of Central Otago I came across two very hairy caterpillars. The were dark brown, the hair was very dense which gave them a velvety appearance, and they were about 25mm long and about 4 mm in body diameter. They were very active and seemed to be travelling. When picked up they curled into a ball like a hedgehog does. Can they be identified from this description?

Brian Patrick, and entomologist at Otago Museum responded.

These densely hairy active caterpillars belong to a species of tiger moth, fascinating and colourful moths of the family Arctiidae to which the more common magpie moth belongs. There are three New Zealand species in the genus Metacrias - all are found in Otago with different species from sea-level to the high alpine zone. An additional three species are found in eastern Australia including Tasmania.

The adult males are attractive, fast-flying and active by day seeking out the flightless buff-coloured females that are hidden beneath rocks or logs. These males are yellow, orange and black with some red colouring and fly on the hottest days of summer. Following mating the females lay many crème-coloured eggs in the nest they have made.

Because the females are immobile, the species builds up quite large colonies and larvae have assumed the role of dispersal. They wander large distances and have even stopped my car on the road to Homer Tunnel as they cross the highway en masse. The dark brown larvae, sometimes with a golden lustre, feed on various grasses and herbs, both native and exotic in natural and semi-natural grasslands.

The eastern hills of Otago are home to two of the tiger moth species - Metacrias strategica is found from sea-level to the low alpine zone while M.huttoni (named for Otago Museum's first curator) is found in the montane to high alpine zone of eastern Otago, being particularly common on the Rock and Pillar Range.