juvenile stage by Kristen Peterson
The Hickory Horned Devil is the largest caterpillar in North America and one of the most unforgettable. It goes through a dramatic transformation, beginning life as a small, dark, spiky creature and growing into a bright green, six-inch-long caterpillar with vivid red horns and a prehistoric look. Despite its intimidating appearance, it is completely harmless!
Early Life
In its early stages, the Hickory Horned Devil is easy to miss. Young caterpillars are dark-colored with long, fine spines and short horns that often have spoon-shaped tips. They may have reddish coloring along their midsection and spend this time feeding on leaves in the canopy of native trees like sumac, walnut, sweetgum, and hickory. This color phase is brief but fascinating, and those familiar with the species may still recognize it even at this early stage.
full size caterpillar by Murray Fisher
Growing Up
With each molt, the caterpillar grows larger and brighter. Eventually, it reaches its full size, glowing green with black-tipped red horns, and covered in subtle blue and yellow markings. This stage typically peaks in August, when the caterpillar prepares for the next chapter of its life cycle.
Pupation stages by Richard Stickney
As summer winds down, mature Hickory Horned Devils leave the trees and begin to crawl across the ground, searching for soft soil. Once they find a suitable spot, they burrow underground to pupate. Unlike many other moths, they do not spin a cocoon. Instead, they remain underground in a tough, smooth pupal shell where they will spend the winter.
Adult Regal Moth by Naomi Zahn (FIRST)
The Final Form: Regal Moth
The following summer, if all goes well, the adult moth emerges. Known as the Regal Moth or Royal Walnut Moth, this beautiful insect is one of the largest moths in North America. It has rust-orange forewings with cream spots and soft gray hindwings with orange stripes. While stunning in its own right, the adult moth lives only for a short time and does not eat—it exists solely to reproduce and continue the cycle.
Why It Matters
The Hickory Horned Devil is not just a fascinating insect… it is also a valuable part of our native ecosystem! Its presence on Fishers Island indicates healthy host plant populations and minimal pesticide use. Like many native caterpillars, it provides food for birds and other wildlife and plays a role in supporting broader biodiversity!
We are fortunate to spot this species on the island. Whether you’re walking a trail or tending your garden, keep an eye out for these incredible creatures and appreciate their place in our shared landscape.
If you’ve photographed one on Fishers Island, we’d love to see it! Share your sightings with us and help us celebrate the wildlife that makes this place so special.
Youth Sentinels
