The Mad Hatterpillar

In 1820, Washington Irving popularized the character of the Headless Horseman, a ghost who terrorizes the countryside looking for his missing head. Though the myth reaches farther into time – Irish folklore, for example, features the Dullahan (“dark man”) who carries his head by horseback – Irving’s The Legend of Sleepy Hallow destined this character to become a Halloween staple.

We eternally ask the question about which is stranger, fact or fiction. The Dullahan and Irving’s Hessian spirit are certainly imaginative and frightening, but nature often produces creatures that rival the best concoctions of humans.

In Australia and New Zealand, an insect does its best job to be the anti-Headless Horseman, in the process dropping Washington Irving for another famous visionary: Lewis Carroll.

Behold Uraba lugens:

Native to Australia, this flier seems to be a typical moth as an adult. In New Zealand, it’s viewed as an invasive pest, and efforts to eradicate it have been extensive. One of the strange attributes of the moth is a layer of hollow hair that contains venom, used to deter predators, which can also irritate human skin. New Zealand had no insects with this adaptation, so they worried about how the moths might affect the human population.

However, these venomous tubes are not the most bizarre part of Uraba lugens.

Nor is it their Halloween-esque non-scientific, common name: gum-leaf skeletoniser.

This macabre, fantastic nomenclature comes from their munching routines. The moth dines on eucalyptus leaves – often called gum leaves – ravenously but avoids the veins, leaving a leaf skeleton to blow in the wind.

How intense is the term “skeletoniser?” And yet, this still is not the moth’s claim to notoriety. This insect displays a truly remarkable trait during its juvenile stage. The skeletoniser’s caterpillar begins looking like this:

These babies look rather gnarly, skeletonizing the leaf and donning long, venomous hair. But they look similar to other moth caterpillars.

The main job of a caterpillar is to eat and eat some more. Eventually, they grow too big for their exoskeleton, so they shed it and grow a new one. Then they ingest again and again. Usually, this process results in the complete dismissal of the previous outer shell.

For the skeletoniser, though, evolution got funky.

Instead of shedding the complete exoskeleton, this caterpillar keeps the head portion. The previous head remains on the body, eventually creating a reverse-nesting-doll stack of pates. It gets so crazy that the head stack looks like a tail.

Each little bump you see on the stacks in the images above is the remnant of a head from an earlier exoskeleton.

For this reason, the skeletoniser is also known as the Mad Hatterpillar, after Carrol’s insane character in Alice’s Adventure’s in Wonderland and Through the Looking-Glass.

What kind of Tim Burton – who counted both Irving and Carroll as film inspiration – version of evolution would produce such a bizarre creature?

A study in 2016 displayed an interesting result. Stink bugs and spiders, the main predators of the Mad Hatterpillar, took ten times as long to attack a bug with a head stack than they did on one with just one noggin. These empty heads could, in essence, become a costume of sorts, pointing predators at fake heads. Maybe this opening gives the caterpillar time to skedaddle or leaves the aggressor with the idea that no real food is coming from attacking this thing. Perhaps the head stack could absorb the pincers, stingers, or teeth of enterprising animals.

Or, just maybe, they developed a heap of heads in case they happened to encounter an angry ghost looking for an extra. Even if the Horseman manages to take one, the Mad Hatterpillar is still in business.