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Goat Moth - Endoxyla bipustulatus
Endoxyla is a member of the family Cossidae, which are renown for their large size and considerable weight. The heaviest moth in the world could well be our Endoxyla macleayi from NSW and southern Queensland, which apparently has an abdomen the size of a small banana, but unfortunately is not often encountered.
These large moths are also called Wood Moths or Carpenter Moths as their larvae bore into eucalypt trunks, where they can do considerable damage if the tree is required for timber; or they will burrow into the roots of certain acacias, particularly in central Australia. The grubs that are the size of your little finger or bigger, are generally known as Witjuti Grubs and have been highly regarded by aborigines for thousands of years. They are also hunted with great determination by many mammals and birds who listen for them and when located will dig them out. The common name of Goat Moth is due to the smelly nature of some grubs of certain species, although adult moths are not likewise affected.
Cossidae according to the Australian Faunal Directory has 20 Australian genera and 87 species, most of which are endemic. The genus Endoxyla is by far the largest with 58 species. Endoxyla bipustulatus has been recorded from Ravensthorpe and Cape Arid, thereby placing Esperance roughly central, but despite this, they are not locally common and if seen at all, is between October and December, even the two recorded collections above were made in November. This timing would coincide with the beginning of warmer weather and a reduction of rainfall, although ground conditions would still be moist and humidity reasonably high.
As Goat Moth larvae usually take 2 and 3 years before they pupate, mass emergence of adult moths are not likely unless their food trees are very numerous, which may reflect their limited numbers in the Esperance region due to a shortage of suitable sized eucalypts. Although with inland mallee regions where there are considerably more eucalypts, it could be a different matter. Anyway, when the larvae do eventually pupate, the newly formed moth will emerge from the trunk, leaving its pupal shell protruding from the tree. Endoxyla bipustulatus is on the smaller end of Cossid moths being around 4 cm or 13/4” in length.