Uraba lugens, the "Gum-Leaf Skeletonizer", is a moth native to Australia. Like all moths, it begins life as a caterpillar, and like all caterpillars, U. lugens eats and eats and eats and eats. Voracious consumers of several species Eucalyptus, younger caterpillars chow down in large groups, leaving only "skeletonized" leaves behind. (Older caterpillars eat alone, and don't even leave skeletons.)

U. lugens caterpillars molt 11 times before forming a cocoon (most moth caterpillars only molt 4 or 5 times), and the caterpillars' bodies are covered in long, irritating spines that cause painful red welts on people unfortunate enough to touch them.

But the most peculiar thing about U. lugens is what it does with its old exoskeletons after each molt.

It keeps the head.

In fact, it keeps all its old heads. And wears them, stacked up on top of one another, like a gruesome totem-pole hat.


Why does it do this? Nobody knows . . . and, in fact, despite being a well-known species, no researcher really seems to care all that much. U. lugens is a eucalypt-murdering pest . . . and now it has established a foothold in New Zealand, where it has no real natural predators. So most current research is less along the lines of "why does it wear a hat-of-ten-heads", and more "how can we murder as many of these things as possible?"

(Which, by the way, is hopefully the parasitoid wasp Cotesia urabae, which was imported to New Zealand in 2010 to control U. lugens populations. C. urabae has its own neat feature . . . in addition to laying eggs in U. lugens caterpillars, it also injects the caterpillars with an immunosuppressive virus. The virus, which can only multiply in special cells in the female wasp's reproductive system, attacks and shuts down the caterpillar's immune system, protecting the wasp-eggs from their host's natural immune defenses, buying the baby wasps enough time to hatch and eat their host from the inside out.)


In conclusion, I really only got interested in this caterpillar because it reminded me of a book I often read as a child:

Caterpillar photos © Nuytsia@Tas, used here without permission. "Caps for Sale" © Esphyr Slobodkina, whose hometown of Chelyabinsk, Russia was recently rocked by an exploding meteor.