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.
Come explore the amazing world of insects with expert entomologists Bryan Danforth and Marina Caillaud (Cornell University). We’ll be out in the
Parade Grounds with sweep nets and bug boxes, catching all kinds of cool critters and learning how to identify them!
This is a fun, hands-on session for all ages, whether you’re a bug lover or just curious about what’s crawling and flying around out there. The entomologists will walk you through the basics of catching, handling, and identifying insects, and they’ll be happy to answer all your questions!
All equipment will be provided. Just wear comfy clothes, closed-toe shoes, and be ready to explore.
Where: The Parade Grounds
When: July 19th at 9:30 – 10:30 AM
Love nature and bugs? Come join entomologist Dr. Adam Mitchell and our awesome FIRST team for a chill evening of insect discovery at the
Parade Grounds!
We’ll be setting up big white sheets and vapor lamps to attract all kinds of cool critters—moths, beetles, and who knows what else! You’ll get to learn about their wild behaviors and help out with our annual biodiversity survey, which helps track native plants and how well the island’s habitats are bouncing back.
Details:
Friday, July 18th, 2025
Starts at 9:30 PM (drop by anytime)
Parade Grounds
Whether you’re a full-on bug enthusiast or just a little curious, this is the perfect chance to experience nature in a whole new way. Bring some friends, your sense of adventure, and let’s see what shows up under the lights!
Sunday, July 20, 2025 | 4:00 PM
FI Movie Theater & via Zoom
The Fishers Island Conservancy is proud to co-host a special presentation by Dr. Doug Tallamy, leading entomologist, conservationist, and co-founder of the transformative Homegrown National Park initiative.
Join us on Sunday, July 20 at 4:00 p.m. for an illustrated talk at the movie theater (also available via Zoom), where Dr. Tallamy will share his compelling vision for restoring biodiversity, starting in our own backyards! Following the talk, there will be a book signing and a reception.
With a national goal to convert 20 million acres of turfgrass into native plant habitat, Homegrown National Park challenges individuals and communities to rethink their landscapes and take action. Tallamy’s message is simple but powerful: we can no longer rely solely on protected wildlands to sustain native species! Real conservation must also happen where people live! On private property, in public spaces, and across working lands.
Drawing on decades of research and outreach, Dr. Tallamy will highlight how native plants support insects, which in turn support birds and the broader web of life. Through engaging visuals and practical advice, he’ll demonstrate how replacing lawn with native species not only helps wildlife thrive, but also reconnects us with the ecosystems we depend on.
A longtime advisor to the Fishers Island Conservancy, Dr. Tallamy’s ecological expertise helped guide the restoration of the Parade Grounds… a living model of habitat renewal that continues to inspire conservation efforts across the island.
Whether you’re a seasoned gardener, a curious newcomer, or someone looking to make a difference at home, this talk will leave you with the tools and motivation to take part in one of the most hopeful grassroots movements in conservation today!
