Magpie Moths

It’s the time of year when one of my favourite moths emerges—the magpie moth (Nyctemera annulata). Magpie moths are in the family Arctiidae—a family including many brightly coloured day-flying moths that threaten to blur the line between moth and butterfly. N. annulata is endemic to New Zealand, though it has a closely related Australian cousin, N. amica, with which it can interbreed.

Magpie moth caterpillars eat plants in the daisy family, especially in the genus Senecio. Common host plants include groundsel (Senecio vulgaris), ragwort (Senecio jacobaea), and cineraria (Jacobaea maritima, formerly Senecio cineraria).

We have large quantities of groundsel, and a few sizeable cineraria on the property, so we always have a healthy population of magpie moths. The caterpillars are black with orange ‘racing’ stripes, and somewhat hairy.

As you can guess from their colouration, magpie moths are poisonous. As caterpillars, they sequester toxins from the plants they eat. These toxins deter most predators. The shining cuckoo, however, is apparently quite fond of magpie moth caterpillars. It avoids the poison by eating only the insides of the caterpillar, leaving the bitter-tasting exoskeleton behind.

In addition to eating weeds like groundsel and ragwort, the magpie moth is a beautiful, colourful addition to the garden. It always makes me smile.