Just look at this picture of this caterpillar with its hats and tell me it doesn’t make you want to giggle, just a little bit.
It keeps its old heads.
What?
Yep, its old heads.
Insects have exoskeletons – hard outer coverings like suits of armour which help them move. Which is kind of nice.
But they also get in the way of their growth, which must be annoying.
So arthropods moult. Shed their exoskeleton and swell up super
quickly before their new one hardens. It’s a really nifty process and is
described nicely here: http://www.insectidentification.org/process-of-molting.asp
That’s why you find cicada shells – they are old discarded exoskeletons. If you look at their backs, you will see the opening from which the growing cicada climbed out.
Caterpillars do 4 or 5 moults before the famous one – that awesome transformative metamorphosis , the biological analogy for almost every rags to riches story.
Oh, and why does this little caterpillar (of the gum leaf skeletoniser moth) keep its old heads like 3D selfies of its
childhood?
Nobody knows. – Maybe it scares of predators – but surely being covered in venomous spines does that nicely.
-it’s a pre-metamorphic, head-stacking, moulty mystery.
Health warning, these little dudes have toxic spines and found in Australia and New Zealand (where they are a
forestry pest). If you see one, PLEASE take a photo and send it to me. BUT PLEASE don’t touch.
Acknowledgements: Thanks to @Bug_girl and her “Bug Girl Blog” for bringing this awesome creature to my attention and also Nuytsia@Tas from flickr.com for the wonderful photo.
Disclaimer: BFFT Metamorphic Analogies Division does not recommend the souvenir collecting of anyone’s heads even your own.