What is a mad hatterpillar? © Alan Henderson/Cover Images

What is a mad hatterpillar?

Mad or fabulous, this caterpillar shows you can go for style and substance with a hat of old heads to swat away predators.

It’s that age-old dilemma. Where to keep all those moulted heads that you’ve grown out of? On the mantelpiece? In the wardrobe? Or on top of your head, like the world’s most outrageous fascinator? If you’re a caterpillar of the Uraba lugens moth, you’ll no doubt plump for the latter.


Nicknamed ‘the mad hatterpillar’, after the Mad Hatter from Lewis Carroll’s Alice’s Adventures in Wonderland, this caterpillar lives in New Zealand and Australia, where it is a serious pest of eucalyptus trees. It munches eucalyptus leaves down to the veins – a talent which has also earned it the name of ‘gum-leaf skeletoniser’ (eucalyptus trees are commonly known as gum trees).

Just like all caterpillars, U. lugens must regularly shed its exoskeleton in order to grow. But unlike other larvae, it doesn’t discard the empty head casings. After the fourth moult, it starts stacking the increasingly large structures on top of its noggin to form what has to be the world’s most bizarre ‘hat’.

Scientists think the unlikely edifice may be anchored by a crown of sticky hairs. Caterpillars use the protruding headgear to swat predators, such as stink bugs, away. How’s that for an excellent hat trick?

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