Hickory Horned Devil

Whoopity-woop-woop ba-doop!
In honor of my first bug ID request (since starting the blog), I'm posting a special, mid-cycle update!

Hey you, with the hand! Let go of my manuscript!

The other day, I got this picture from my sister-in-law. Imagine, finding a perfectly good piece of paper like that on the ground! Also, there's an interesting bug on the paper. That's not her hand in the picture. Her friend's dad was at work and he and some co-workers came across it - the paper, as well as the bug, that is.

This little devil is a caterpillar called the Hickory Horned Devil (heretofore referred to as HHD). Sometimes caterpillars are so unique or recognizable that they get their own name, independent of the moth or butterfly that they pupate into. The HDD is one of these, for obvious reasons. HHD caterpillars are the larval state of the moth known as the Regal Moth (also sometimes called the Royal Walnut Moth). Both of these are among the  largest caterpillars and the largest moths in North America.

After hatching from an egg laid just a few days prior, the tiny, nondescript blackish or sometimes yellowish caterpillar quickly turns a splotchy black and white. They mostly feed at night on leaves of several types of trees (including hickory, oak, and sumac). In a short amount of time, they become the giant caterpillar with the crazy horns and spikes that you see in the picture. The pictured HHD is probably in its 6th and final instar (or growth stage) before it pupates into the Regal Moth. After ravenously feeding in its 4th and 5th growth stages, it changes color from a garish, bright green to the turquoise-green seen in the pic above. It then makes its way to the ground, digs itself a nice little hole, and forms a pupa (looks kind of like a black or 80% cacao dark chocolate-brown babushka, all wrapped up and swaddled). It then goes through the lengthy process of transforming itself from an HHD to a Regal Moth.

Science Photo Library (sciencephoto.com)
provided this pic of a female Regal Moth waiting
for some dudes to show up with margaritas.

The HHD pupa overwinters in the ground and emerges in midsummer as the Regal Moth - one of the largest North American moths. Like another bug I recently wrote about (see post on the Dobsonfly), the adulthood of the Regal Moth is brief and has only one purpose: make more Regal Moths. After emerging from the pupae and drying off, adult Regal Moths typically live for about a week. Like newly minted adults on spring break, the males typically have more fun during their week of freedom than the females do. The males will usually try to mate with as many females as they can during that week, whereas females are stuck with their one clutch of eggs after a single hookup.

There are other interesting things about HHDs and Regal Moths. First, they are closely related to the Giant Silkworm Moths and are traditionally grouped into the same Family (Saturniidae). But more modern sources group Regal Moths into a separate family: the Royal Moths (Citheroniidae). This is largely due to several subtle wing differences, but can be superficially attributed to the lack of large, eye-like wing spots. Luna moths are among the most well known and most recognizable Giant Silkworm Moths in the Eastern US and these big eye spots are one of their defining features. You may remember the Luna Moth from sleeping pill commercials as the somewhat creepy, big, green fairy-like (absinthe connection?) moths that flap around people's bedrooms and even tuck them in (no way that a moth could lift and pull up someone's sheets). Although, the Lunesta commercials mostly misrepresent Luna moths. I'm not sure how, other than pharmacalogically assisted, someone would be able to sleep knowing that a sentient, giant, glowing moth was sitting on the pillow next to them...all night...watching them sleep, until daylight come (tally me banana!).

Other interesting facteroonies about the Regal Moth (Citheronia regalis) have to do with their pre-adulthood, before all the responsibility of mating as much as possible in a week (wasn't that the premise for Porky's 3?!) weighs them down. While swaddled like a newborn in their pupal state, they will typically overwinter underground for quite a few months - September to July is typical. But, a significant minority of the population will actually stay underground for a whole extra year! This is presumably to keep the gene pool mixed up. But I suspect it has a lot to do with all the weight they put on while gorging themselves as caterpillars.

Although HHDs have a pretty showy and dangerous-looking display of spikes and horns, none of them contain any poison and HHDs are actually considered one of the more easily handled large caterpillars. It's all just for show! They're born with their antlers deflated, and it's normal for them to spend 20 or 30 minutes inflating them (with hemolymph, or bug-blood, I believe) while eating the shells of their eggs. But when they're very young, they rely on another form of visual trickery for defense. I mentioned earlier that they quickly turn from blackish or yellowish to black and white splotched. Well, when they curl up into a J-shape during the day, they look surprisingly like bird poop. Since exactly 0 birds like to eat bird poop (contrasted with the many birds that like to eat caterpillars), this is a pretty good defense - a lot like the fake cans of Barbasol or Scotch Guard you can buy at the Container Store to hide your valuables in. But the specifics of this defense beg the question: did natural selection lead to this caterpillar's doo-doo-camo, or was it the HHD's own self-loathing that made its outsides look like it felt on the inside?

Before I finish, I'd like to get all guidance counselor for a minute and have a very special sidebar with the HHD - a little heart-to-heart, if you will (right now I'm turning my chair around and sitting on it backwards so that I seem more at ease and relatable).

Hickory Horned Devil - can I call you Hicky? What's with you these days? You're no devil and everyone knows that those horns are just for show...just to keep people away. I want to know what's going on with that guy in there. Why won't you let anyone in? Sure, you looked like crap when you were younger - but that was only because you made yourself look that way. Now you look all dangerous, but is that just so that no one bothers you about your weight? We're worried about you, Hicky. We all saw how you ate all those hickory and oak leaves all by yourself. I'll tell you what I don't want - I don't want to come back here in a year and find out that you're still hiding underground. Look - I'm not trying to give you a hard time or come down on just you...but I'm also worried about your future. We all are. I mean, what will you do once you grow up and can't stay in your pupal case any longer? I'm worried that you'll come out of the ground and spend your whole adulthood making risky decisions; jumping into bed with everyone you meet and, in the end, have nothing to show for it but a bunch of kids from a bunch of different baby-mamas, who end up living the same downward spiral that you've been on all summer. Thanks for listening, Hicky.

And thank you for reading! In addition to my regular posts, I plan on responding to a number of other identification requests in the coming two weeks. These posts may be shorter and more to the point than you're used to, but I'm sure you'll enjoy them!

That girl bad looking like a bag of money; I go and get it and I let her count it for me.
 - William Leonard Roberts II (AKA, Rick Ro$$)