Monday, April 7, 2008

From Out of the Earth

We found two of these last weekend - one on the ground next to its hole and one half out. Of course the casings were empty, and we guessed that they had been the pupa of something large, as they were around three inches long.
Friend Snail came to the rescue and told me they were very likely to be goat moths - or were goat moth pupa before the moth came out and flew away. That sent me Googling to discover that the larva is from the witchety grub family (of edibles!). I can see why a few of these would make a good meal. If you could eat them raw, as the Aborigines do.
Apparently the goat moth larvae like wattles - or acacias - and the larva burrows deeply into the trunk of the tree. When it's ready for the next stage, it burrows down into the ground where it stays until "hatching". Often it doesn't come completely out of the ground, but leaves the casing behind (as in the photo above).
I imagine these are big moths, although I couldn't find anything that told me their average wingspan, but we'll be keeping a lookout for them at dusk.
This might also explain why so many wattle trees up there tend to fall over!


Snail said...

You're not going to be impressed with me but now I've had another look, I think it's a ghost (or swift) moth pupa --- family Hepialidae. (In my defence, I couldn't get a big version on my computer. Yeah, weak, I know.) They have much the same life cycle as the goat moths.

But --- and this is a big one --- if it's Aenetus, then you're in for a treat. So are the owls and frogmouths. For you, it'll be the colour --- they're often a delicate green. For the owls and frogmouths, it's that fat, juicy abdomen.

Sherryl said...

I'll certainly be keeping an eye out, either way! Something big, being chased by an owl.
You might have been right the first time though - none of the trees listed are where we are (that the ghost moth eats) and we may not be wet enough either.
Still, it's all fascinating for me! And I do appreciate your help - thanks.

Junior Lepid said...

Either Cossid or Hepialid. If you have any eucalypts in the vicinity, I'd be thinking Trictena atripalpis (fairly large Hepialid) as I've found they are one of the first to emerge in Autumn after a bit of rain.

Well, they do up my way! :-)

Sherryl said...

Thanks for this - we have a few thousand eucalypts! Messmate, peppermint, ghost gum - plus others. And this was definitely autumn.

Junior Lepid said...

But wait....the Cossids (Goat Moths) also emerge in Autumn! You would need to have a look at the adult. Most males of both species come readily to light - so next autumn - after some rain, leave an outside light on in the evening for a while and see what comes forth!

All is not lost, a bit of observation around springtime could be beneficial!

Nature Blog Network