Thursday, 1 November 2012

The Pink Underwing Moth: Skull-Faced Caterpillar of Australia’s Rainforest


Nature never ceases to astonish.  This is the larva of the Pink Underwing Moth, an endangered species which lives in the subtropical rainforest below about 600m elevation in the Australian states of New South Wales and Queensland. It has evolved a remarkable set of patterns to ward off potential predators.

A giant set of eyes would, you might think, be enough to warn off a bird looking for an easy lunch. Yet this caterpillar goes one step further.  It appears to have a set of teeth which could rip any possible attacker to shreds. Why, then, is it so rare? You might think that with this sort of natural protection the species would be thriving everywhere.

That might be true, if it were not for the fact that the caterpillar of the pink underwing (a subspecies of Phyllodes imperialis) is something of a fussy eater. Prospective breeding habitats are restricted to places where the caterpillar's sole food plant, a rainforest vine, Carronia multisepalea, grows in Australia’s eastern subtropical rainforests. The plant is rare, so likewise is the pink underwing. In fact the larva has only been found in six places.

When they hatch the caterpillars are at first a dull brown color.  At this stage in their life cycle they rely on something called crypsis to avoid detection. It does this by having the appearance of a dried up leaf. Yet when it gets larger it relies as much on its markings as it does its ability to blend in.

As the caterpillars grow they develop these two large eye spots bordered by thin yellow rings. Then there is that savage looking double row of white teeth on the dorsal side flanked by the eye spots.

The most surprising thing, perhaps, is that these remarkable markings are at the larva’s bottom end, as it were.  The real head is curled up, as are its legs. What we see is the anterior body segments raised up: as the skin stretches the markings are revealed. Enough to frighten away anything, one hopes.

Very few sightings of the caterpillar or the adult moth have been made this year, provoking fears that this highly endangered species is on the point of extinction. It is threatened by clearing of the rainforest as well as invasion by exotic vine species which have superseded its own favored food. Unfortunately, too, when a population becomes so low that too becomes another issue – the adults simply do not encounter each other regularly enough to mate.

Yet the Australian government is not sitting back and doing nothing.  It plans to identify high priority sites and make sure that if these areas are on private land that they must be conserved.  They are also providing people with information about habitat and encouraging the regeneration of the primary rainforest in which the moth lives. Let’s hope that this amazing species gets the support it needs to survive.

Ark in Space would like to thank Flickr Photographer plant.nerd for their very generous permission, allowing us to use these photographs. Please visit their wonderful photostream to see many wonderful photographs.

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