Giant Wood Moths (Endoxyla cinereus) are so big that people sometimes mistake them for small birds. They occasionally appear in summer in the outer suburbs of Sydney. This female was photographed at North Richmond near the Hawkesbury River. The species is found from northern Queensland to southern New South Wales.
Adult female Giant Wood Moths have a wingspan of up to 25 cm and are among the heaviest moths in the world (weighing up to 30 grams). The males are smaller and have feathery antennae (the females' antennae are slender).
Female Giant Wood Moths pump up to 20,000 tiny eggs into crevices in eucalypt tree trunks and branches, covering them with a glutinous secretion that hardens and protects the eggs. Once hatched, the very small caterpillars lower themselves to the ground on silk threads. Biologists think they spend the first months of their lives feeding on underground roots before they burrow into the trunks of trees.
Giant Wood Moths spend most of their life as caterpillars, eating the soft plant tissue that the tree produces to repair the damage from the caterpillar's burrowing. The caterpillars take two years to grow to full size (about 15 cm for females), then shed their skin and form a hard pupal case with spines on the outside. When the pupa is mature, it wriggles halfway out of the burrow and the golden-brown case splits, allowing the moth to emerge from the case and dry its wings before moving away. Giant Wood Moths live for only a short time as adults and don't feed in this stage of their life cycle.
January, 2004
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