Hickory Horned Devil

This post is several weeks later than what I said it would be, but better late than never! Back at the beginning of September, I went to a caterpillar party (because that is the kind of party wildlife biology majors have) in northern Athens County. I made a post earlier on some of the more showy caterpillars we found over the course of the night, which you can read here. However, I felt the star of the night deserved a post all his own, and so here we are!

Meet the Hickory Horned Devil, Citheronia regalis. This awe-inspiring creature is the larval stage of the Regal Moth (also known as the Royal Walnut Moth). I'd like to go on a quick tangent for a second. That's a lot of names for one species, isn't it? This highlights one of the several problems with common names. All species, once discovered and described, are given one specific scientific name. In this case it's Citheronia regalis. There is no other animal with that name. If someone says that name, everyone knows what species they're referring to. On the other hand, common names are not that straightforward. The caterpillars are mostly called Hickory Horned Devils, but you could also correctly call it a Regal Moth caterpillar. The adults aren't often called Hickory Horned Devils, but instead are called Regal Moths or Royal Walnut Moths, depending on which you prefer. With so many names, it's easy for people to get confused and not know exactly what you're talking about. Often times, common names vary across geographical regions and from person to person, which is why I always give a scientific name (the specific two-part Latin name) in my posts in addition to a given common name. 

Naming aside, this is a monstrously-large caterpillar, as you can tell by the photo above. In fact, this is the largest caterpillar species in North America. It is worth noting that the adult moth isn't the largest moth in North America though (a title belonging to the Cecropia Moth). Although it might look terrifying (especially to those who aren't that keen on insects), the Hickory Horned Devil is completely harmless. The large horn-like projections on its head, which are technically named "scoli" (singular: scolus), are modified tubercles. You might think that these scoli can sting, as certain caterpillars can do, but these are only for show and they can't really harm anything. The Hickory Horned Devil runs solely on the bet that its appearance will scare off any potential predators, which is quite effective for the most part.

As you might have imagined, this caterpillar caused quite the ruckus amongst the group. I was taking photos of another caterpillar when I was completely startled by excited screaming coming from behind me. Although I had no idea what people were screaming and hooting about, I knew it was going to be something good. Running over, I was utterly dumbfounded to see them surrounding a bent sapling with the Hickory Horned Devil munching away on a leaf. I honestly have no idea how the person who found it saw it to begin with; once we were all done admiring the caterpillar, we gently released the tree. As you can see in the photo above, the caterpillar doesn't exactly stand out much, even with its size (he's in the top right). Whoever first saw it must have had incredibly sharp eyes.

As you might have guessed, the Hickory Horned Devil likes to feed on various hickory species, but, like many other caterpillars, will also feed on a variety of other trees including Black Walnut, Sweetgum, Persimmon, Buttonbush, and assorted other species.

Late in the summer, around when we found this individual, the mature caterpillars will begin to descend the trees they are feeding on in order to get ready for the next step in their life cycle. Upon reaching the ground, the Hickory Horned Devil will find an appropriate place to burrow into the soil in order to pupate. They will stay in this stage over the winter and will emerge as an adult moth either during the next summer or the summer after.

This Hickory Horned Devil was the find of the night, by far. There were many cheers and many cries of victory for this caterpillar, and of course there was also person after person taking photos of it (like Olivia Brooks in the photo above). Overall, the caterpillar night was a smashing success, and it will hopefully become an annual event!