It's got a face that lives up to its name.
Stuart Brisco, of Point Lookout, Missouri, had no idea it was living in his back yard.
The bizarre critter was a 5.5-inch-long hickory horned devil caterpillar, nearly as fat and plump as a hot dog. They can grow to be 6 inches long and are the largest caterpillar in Missouri.
A construction crew doing some work at his house spotted the big green caterpillar making its way across some excavated dirt.
"It makes sense because after some research I found out that at this stage the caterpillar will find fresh soil to burrow into before it pupates into a moth," Brisco said. "My wife, knowing I would not want to miss out on seeing this cool creature, placed it in a five-gallon bucket until I got home from work. She sent me pictures and I was amazed by the size of the animal, but they did not do it justice."
Though fearsome looking, with its long spikes and big fake eyes, the hickory horned devil is harmless to humans. After it pupates underground, it sheds not only its long spikes and impressive size, but also its wicked-sounding name.
It emerges in the summer as a Regal moth, with orange, brown and yellow markings across its 6-inch wingspan. Regal moths are nocturnal fliers, occasionally seen fluttering around porch lights or yard lights.
The caterpillar phase of this creature dines on the leaves of many familiar Missouri trees — walnut, pecan, sweetgum, hickory, and persimmon. They'll also chew on the leaves of sumac bushes.
"Never did I know this caterpillar was in Missouri, so we had to look it up, which did not take any time due to its striking features," Brisco said. "This particular one measured roughly 5.5 inches and felt surprisingly heavy. Even though its features might make it appear frightening to some people, it was a gentle giant and was easy to handle."
He released the caterpillar to continue its search for a nice hole in which to transform into a Regal moth.
"To anyone that might be fearful from the looks of these creatures I would simply recommend admiring from a distance and simply leave nature alone," he said. "You never know what surprise you can come across in nature."
Chris Barnhart, professor of biology at Missouri State University, said hickory horned devils and Regal moths aren't particularly rare, though not many people see them.
"They are pretty well camouflaged," he said. "It is unusual for people to find one."
Unlike some caterpillars that are poisonous to the touch, Barnhart said the spikes of a hickory horned devil aren't toxic.
"They are not dangerous, no," he said. "But they can start thrashing around and make someone drop it. These (and their Regal moth form) are beautiful and kind of mysterious."