I begin this story with yet another insect scooped up off the steps of Helensburgh Railway Station, where it was in imminent danger of being flattened. What a great place for insects the station is!
This large moth is Chelepteryx chalepteryx, aka the enigmatically named ‘White-stemmed Acacia Moth’ (anybody seen a white-stemmed acacia? Its larger relative Chelepteryx collesi is called the white-stemmed gum moth – so maybe somebody forgot to drop the ‘white-stemmed’ bit for our moth. All the more reason for using the scientific name). The food plants vary from acacias to Gymea lilies. That’s my amazingly clean hand for scale. This is a female – the male has feathery antennae and flashier underwings.
This moth belongs to the Anthelidae, a family restricted to Australia and New Guinea. Chelepteryx is a typical anthelid genus, characterised by huge caterpillars having nasty urticating hairs, which are also embedded in the silk coccoon made around the pupa.
Urtication means severe irritation, and is named from the effect of handling Urtica, the nettle, but the name Urtica itself means a burn. Contact with the hairs from anthelid caterpillars may require hospitalisation. So this is not really the sort of moth to bring home to rear caterpillars from. Another member of the nettle family is our giant stinging tree, Dendrocnide, for which the phrase ‘one bitten, twice shy’ is particularly apt.
The moth itself seems harmless. Strangely, this large insect can’t feed, it has no mouthparts. It has been a hungry caterpillar for a year but only lives for a few days as an adult, despite the careful details on the wings that help it to hide – the false scars from insect damage and mottled browns of old leaves. Lack of feeding in very large adult insects seems quite common – for example, in some stag and longhorn beetles. Perhaps large adults are too easy to find and eat, and therefore have to get on with it as quickly as possible – ie mate and lay eggs. The literature for Chelepteryx notes that discovered females like mine often lay eggs, suggesting that they mate as soon as they hatch at the cocoon.
Another urticating caterpillar, which may be more familiar, is that of Leptocneria reducta, the White Cedar Moth. It completely defoliates white cedar (Melia) and then wanders around to pupate. We have a white cedar next to the house and always seem to end up with cocoons at the back of pictures or under chairs. Leptocneria is in the family Erebidae and completely unrelated to Chelepteryx, but is doing much the same thing, and also has short-lived non-feeding adults. This is a classic example of convergent evolution, like the wings of bats and birds.
Further information
Australian Moths:
Moths of Australia, by Ian Common, 1990. Melbourne University Press.
Chelepteryx:
http://lepidoptera.butterflyhouse.com.au/anth/chalepteryx.html
https://australian.museum/learn/animals/insects/white-stemmed-gum-moth/
White cedar moth:
