The Caterpillars live and feed communally inside the tough leathery (and prickly) skin of the host plant, reducing the plant material insideto a gooey green mess.The Caterpillars are initially pinkish-cream coloured,with dark red dots on the back of each segment. Later instars become orange, and the dots expand and then fuse to become a dark band across each segment.The Caterpillars grow to length of about 1.5 cms.

They normally pupate in white cocoons amongst the ground debris. In captivity, some pupated at the top of their jar, and some at the bottom.

The adult is fawn with faint dark dots and lines on the wings, and has a long nose. It normally rests with its wings wrapped around its bodyThe moth has a wingspan of about 2 cms.

(Specimen: courtesy of the Macleay Museum, University of Sydney)

The species was originally found in Argentina, but was introduced to Australia in 1926 by the release of 2,000,000 eggs near the town of Chinchilla, in order to control the Prickly Pear which was overtaking much of Queenland. For the same reason, the species has been introduced into other countries, including:

mating pair of adult moths

The species is now common over Queensland and New South Wales, and the Prickly Pear has been reduced to isolated plants of little economic significance. Unfortunately, the species has also spread to the mainland of north America, and has become a pest there on the local cacti.

egg pile on a cactus spine

The eggs are laid on top of each other like a stack of coins, the first one being anchored to a cactus spine. The stack can contain over 100 eggs, and curves over to make a kind of bent stick with a length of up to 2 cms. When they hatch, the young caterpillars walk down the stick and start burrowing into the cactus.

Ascension Island, 1998

Further reading :

Ian F.B. Common,
Moths of Australia, Melbourne University Press, 1990, pp. 58, 72, 349.

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