Goat Moths after the rain

Many people in this area will have seen large grey-brown moths appear after the wonderful rain we have experienced.  About the size of a tennis ball (in diameter) they are Swift Moths of the Family Hepialidae. The young larvae of these moths (also known as “Witchetty or Bardi grubs”) nibble surface vegetation before burrowing into the soil where they feed on roots (grasses, eucalypts). The genus shown is Abantiades*. The caterpillars pupate into a honey coloured casing from which the adult moth emerges, usually after late summer or autumn rain. There is an excellent summary of information at http://en.wikipedia.org/wiki/Witchetty_grub.

Adult Swift Moth (Newstead, April 2009)

Adult Swift Moth (Newstead, April 2009)

* Note that I orginally misidentified this as a Goat Moth (Family Cossidae). Many thanks to Mike Halsey for picking up the error (see comment).

7 responses to “Goat Moths after the rain

  1. I often wondered what the caterpillars we often find in trees and coming out of our hard ground are. Would these be the same tunneling caterpillars that Alison Pouliot described being consumed by fungus whilst in the ground?

  2. A very good question! My understanding is that the “caterpillar eaten by fungus” phenomenon is part of the ecology of our bush soils and not unique to a species……would be very happy to hear more on this topic!

  3. From my understanding, moth larvae of the genus Oxycanus are the hosts for a group of very specialised parasitic fungi of the genus Cordyceps. The one I presented in the Newstead talk is Cordyceps gunni which was parasitising a goat moth in its larval stage. The fungus moves through the soil and infects the larva, utilising the nutrients and then produces a greenish-black club-shaped fruiting body, sometimes up to 12-15cm high. They’re certainly a fascinating and somewhat kooky group! hope this helps. Regards
    Alison

  4. The image and the behaviour described is actually of members of the Hepialidae (vernacular: Swift moths), not the cossidae. Hepialidae lays eggs by scattering while on the wing. The young larvae of most of this family nibble surface vegetation before burrowing into the soil where they feed on roots (grasses, eucalypts). The genus shown is abantiades – the larvae are often referred to as bardi grubs. The larvae of the cossidae (“goat moths”) generally feed on living or dead wood, often in standing trees.

  5. Many thanks for correcting this error Mike. I’m certainly no moth expert and must admit I did have some doubts about the ID. I’m sure readers of the Natural Newstead blog will be pleased to have the right information. I’ll fix the post up shortly.
    All the best, geoff

  6. I wonder if these are the moths we get in large numbers every year at this time. They seem always to come out when it rains, even when it is very cold. Their bodies are brown and seem to extend to well over an inch/ two centimetres plus as they flutter at the lighted windows. Wing span is perhaps 7 centimetres. I come across quite a lot of big grubs when digging the garden and suspect these might be the culprits! David, Exeter, Southern Highlands NSW

  7. greetings.l’m interested in locating licensed breeders for moths… specifically the “rain moth” or trictena atripalpis. l would like to purchase several for scientific study. thank you for your attn to this question. dave

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