The hickory horned devil, scientifically known as Citheronia regalis, is a remarkably large caterpillar with an intimidating appearance. Although this creature might seem threatening, it’s important to note that it is actually harmless to humans. Found commonly feeding on leaves of walnut, hickory, pecan, persimmon, and sweet gum trees, these sizable caterpillars are intriguing subjects worth exploring.
Before growing into regal moths, hickory horned devils go through multiple stages of growth and molt. As gigantic blue-green caterpillars, they come with long, black-tipped spines and curved orange horns, which might lead one to worry about the possibility of poisoning. However, these fascinating insects should not be avoided out of fear; instead, we can appreciate this unique species from a safe distance, observing all it has to offer.
Hickory Horned Devil: General Overview
Identification and Appearance
The hickory horned devil, or Citheronia regalis, is a large and colorful caterpillar often seen in North America. Despite its intimidating appearance, it is harmless. The caterpillar has:
- Turquoise-blue body
- Black spines on each segment
- Horn-like structures on the second and third thoracic segments that are orange with black tips
These distinctive features make it easy to identify the hickory horned devil.
Habitat and Distribution
The hickory horned devil can be found primarily in the eastern United States, ranging from the south up to southern Massachusetts. Its habitat mainly includes:
- Walnut trees
- Hickory trees
- Persimmon trees
- Sycamore trees
- Ash trees
The caterpillar feeds on the leaves of these trees during the summer months. It later transforms into the royal walnut moth, a nocturnal creature rarely seen due to its nighttime habits. The moth mates and lays eggs in these regions, and the larvae grow into the hickory horned devils to continue the life cycle.
Life Cycle and Behavior
From Caterpillar to Moth
The hickory horned devil (Citheronia regalis) starts its life as a tiny caterpillar hatched from an egg laid by a regal moth. Over several weeks, it grows and molts through different instars, eventually reaching a mature size of approximately 5.5 inches (14 cm) long1. Despite its ferocious appearance, the hickory horned devil is harmless, with non-poisonous spines2. When ready to pupate, the caterpillar leaves its host plant and finds a suitable spot in the soil to create an earthen chamber3.
Within this chamber, the caterpillar transforms into a pupa. After a period of around nine months, the regal moth emerges from the pupae, signaling the end of the life cycle4. Adult moths are nocturnal and not commonly seen.
Feeding Habits and Host Plants
Throughout its life as a caterpillar, the hickory horned devil feeds on various tree leaves:
.Characteristics of Hickory Horned Devil and Regal Moth
|Hickory Horned Devil (Caterpillar)||Regal Moth (Adult)|
|Non-poisonous, harmless spines2||Nocturnal, rarely seen10|
|Feeds on tree leaves8||Does not feed9|
|Creates an earthen chamber3||N/A|
Is the Hickory Horned Devil Poisonous?
Physical Features and Toxicity
The hickory horned devil (Citheronia regalis) is a large caterpillar with a striking appearance. Some of its distinct features include:
- Pea green to blue-green body
- 4 to 5 inches in length
- Two pairs of yellow to orange curved horns
- Paired rows of spines down the back
Despite its fierce appearance, the hickory horned devil is harmless. It doesn’t produce any toxins and is not poisonous. The caterpillar typically feeds on the leaves of hickories, pecans, sweetgums, and sumac in deciduous forests.
Potential Threats to Humans
Although the hickory horned devil caterpillar may appear intimidating, it poses no real threat to humans. Its spines and horns are not venomous or harmful. In fact, the caterpillar is quite rare in the wild, minimizing the chances of human encounters.
Comparison between the harmless hickory horned devil and potentially dangerous caterpillars:
|Feature||Hickory Horned Devil||Potentially Dangerous Caterpillars|
|Size||Large (4 to 5 inches)||Varies (usually smaller)|
|Color||Pea green to blue-green||Varies (can overlap with hickory horned devil)|
|Spines/Horns||Yellow to orange curved horns; paired rows of spines||Can have urticating hairs or venomous spines|
|Toxicity||Not toxic or poisonous||Can cause skin irritation, rashes, or even systemic reactions|
In conclusion, the hickory horned devil caterpillar is an interesting and fascinating creature. Its unique appearance may lead many people to think it is dangerous, but in reality, it poses no real threat to humans.
Conservation and Population Status
Decline in Numbers
The hickory horned devil (Citheronia regalis) is a rare and unique creature. Due to factors like habitat loss and decreasing host plants availability, their numbers have been declining. Some specific threats include:
- Loss of hickory-type trees, pecans, buttonbush, filbert, and persimmon leaves
- Introduction of non-native predators
- Human disturbance
Efforts to Protect Hickory Horned Devils
There are various actions we can take to help conserve the hickory horned devil population. Some examples are:
- Protect and conserve their natural habitats, specifically in New England and New Jersey
- Plant more host trees on which they feed and lay their eggs
- Educate the public about these fascinating creatures and their importance in the ecosystem
Comparison Table: Hickory Horned Devil vs. Other Saturniidae Moths
|Feature||Hickory Horned Devil||Other Saturniidae Moths|
|Binomial Name||Citheronia regalis||Varies|
|Appearance||Large, green body, yellow markings, horn-like mouthparts||Varies, often vibrant colors and patterns|
|Host Trees||Hickory, pecans, buttonbush, filbert, persimmon||Varies, often specific trees|
|Natural Distribution||New England, New Jersey||Worldwide, depending on species|
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – Royal Walnut Moth
Large orange moth
June 28, 2010
We have a wide variety of moths each day in the foyer of our apartment complex, but this morning I saw something completely different next to my neighbor’s door. It is the largest moth I have ever seen, next to a Luna Moth. I originally thought it may be a Cecropia Moth because of the orange body, but the markings on the wings look different than any photos I have found online.
Good Morning Shelly,
Your lovely moth is a Royal Walnut Moth, Citheronia regalis, is the adult form of the largest caterpillar in North America, the formidable looking Hickory Horned Devil.
Letter 2 – Royal Walnut Moth
Subject: Moth-like bug
Geographic location of the bug: Concord, North Carolina
Time: 11:05 AM EDT
Your letter to the bugman: Hello! I saw this interesting bug on my back porch, and I can’t identify it.
How you want your letter signed: No
Letter 3 – Royal Walnut Moths Mating
Unusual Moth… Need Help Identifying..
A friend in South Carolina sent me this pic of two moths that he found resting on his gate… He stated that he was a matter of inches away and they didn’t even flutter… Can you help to identify what sort of moth they are? Thanks so much..
We believe these Royal Walnut Moths, also known as Regal Moths, are mating.
Letter 4 – Royal Walnut Moth
Hi! The bottom of this moth is all yellow with red spots and 6 legs. The main colors are obvious. His body was super big about 4 inches. Your site is super informative and i did some research and i cannot identify this moth that i found. any suggestions? thanks again!
We have gotten several photos this year of the Royal Walnut Moth or Regal Moth.
Letter 5 – Royal Walnut Moth
What is this?
Came home from vacation and found this huge moth? laying eggs on my apartment wall. It is at least 5 inches long. Any idea what it may be? I am from Columbia MD.
Wonderful photos of a Royal Walnut Moth, Citheronia regalis, also known as the Regal Moth. The incredible looking caterpillars are known as Hickory Horned Devils and Hickory and Walnut are two major food plants eaten by the caterpillar. Adults do not eat.
Letter 6 – Royal Walnut Moth
Have any idea what this is? My neighbor found it on her deck. It is about 3-4 inches long and just sitting there. So I took a picture and hope you can id it.
Liz in Louisville KY
In September, we get photos and letters about the Hickory Horned Devil, a very impressive caterpillar, but we have never gotten a photo of the adult moth, until now. Your Regal Moth is also known as a Royal Walnut Moth, Citheronia regalis. The caterpillar feeds on hickory, walnut, butternut, ash, sumac sweet gum and persimmon. It ranges throughout the eastern U.S. and Canada, but is most common in the South. Adults are short lived and do not feed.
Letter 7 – Royal Walnut Moth
Giant orange striped fuzzy mutant moth creature!
Hello! I found this giant orange striped fuzzy moth creature at my work here in Pittsburgh PA near the airport runway. I have never seen something like this before, nor has anyone I work with… we are hoping you can help us identify this mutant moth! Thank you.
Despite sending us this photo in January, we suspect you encountered this Royal Walnut Moth or Royal Moth sometime in the spring. This is the adult form of the frightening but harmless Hickory Horned Devil. Both caterpillar and adult moth are quite striking and spectacular.
Letter 8 – Royal Walnut Moth
This large moth, about 1.5 inches, came to sleep on a sage plant in my herb garden this past July. He stayed all day but slipped away when we were not watching in the evening. Very pretty and fuzzy. Photos courtesy of my wife Nancy.The stripes are alternating orange and gray-green. A cream color completes the wardrobe. I have looked at all the moths on your web site without finding a match. We see Luna Moths about every other year and this had a similar size body but not so big a wingspan. We live in Apex, NC, a suburb of Raleigh and Research Triangle Park. Our back yard is wooded and the houses across the street are heavily wooded. We can see a large lot with a small field and a small pond. So there is a mix of habitats. No farming in the area, mostly homes and shopping. We feed birds and keep baths and several types of feed going. We get lots of cottontail rabbits and squirrels, the occasional owl comes through and we now have a couple of pairs of resident hawks in the area. We do have a lot of flowers in front and see hummingbird moths often in late summer. We are hoping you can help us.
Robert and Nancy Bickle
Hi Robert and Nancy,
It sounds like you have an enviable domicile. This is a Regal Moth or Royal Walnut Moth. The caterpillar is the Hickory Horned Devil and is going to be our featured bug for September.
Letter 9 – Royal Walnut Moth
2 pictures for you
My husband found this moth outside his work in Pittsburgh, Pa, and we tried to find a picture like it with no success. Is is about 3 inch across, and very pretty, as you can see. Thank you if you can help.
Mary Ellen Goff
Hi Mary Ellen,
The Royal Walnut Moth is also known as the Regal Moth and its caterpillar, the Hickory Horned Devil, is equally spectacular.
Letter 10 – Royal Walnut Moth Laying Eggs
Photo to share, if that’s okay.
Hello, my mom saw this Royal Walnut Moth on the side of our house in southeast Pennsylvania. Your website is awesome, it was my only way to ID the moth–even enature.com (my other-animal-ID-place) didn’t have it! Anyway, it laid eggs and a few had fallen to the ground, seemingly unharmed, so I’m going to see if they hatch, with my 4-year-old sister. Just thought I’d share my photos, in case you wanted to use them. If not, that’s fine too! Thanks again!
Your photo is lovely, but what we really like about it is the eggs. Insect eggs are often very difficult to identify and we get numerous requests. We will be posting your image and letter on several of our pages, including the egg page. If the eggs hatch, and you have the opportunity to see a grown caterpillar, they are very impressive. We get photos of the Hickory Horned Devils in September and we have many photos of them on our numerous caterpillar pages.
Letter 11 – Royal Walnut Moth
Is this Sphinx Moth?
I tried to identify this beutiful moth, but found your site… Can you please identify it for me? This was found today in Murfreesboro, Tennessee. Its wings spans 3-4"wide when it opens. Thank you.
This is not a Sphinx Moth. It is a Royal Walnut Moth or Regal Moth, one of the Saturnid or Giant Silk Moths.
Letter 12 – Two Royal Walnut Moths
a picture for you
What is this bug. Two of them stayed on that fence post all day. thanks,
This gorgeous moth is the Regal Moth or Royal Walnut Moth, the adult of North America’s largest and most striking looking caterpillar, the Hickory Horned Devil.
Letter 13 – Royal Walnut Moth or Regal Moth
Moth found at Fort Campbell TN
can you tell me what kind of moth this is?
This is a Royal Walnut Moth or Regal Moth whose caterpillar is the striking looking Hickory Horned Devil.
Letter 14 – Royal Walnut Moth laying eggs and newly hatched Hickory Horned Devils
Thanks so much for identifying the Pearly Wood Nymph for me. I received your email this morning to my great surprise. Boy you are fast. I thought it might be the Pearly from you page but didn’t know for sure. Thought you might be interested see a Royal Walnut Moth that laid her eggs on the siding of my front porch almost two weeks ago. She had lots of babies but I don’t know about the survival rate. We saw a lot of dead babies and didn’t know if it was because she didn’t lay them on a host plant that they could start eating. Not two days after all the eggs had finished hatching I had a Small Eyed Sphinx. Such velvet wings. My bug friend identified it from my pictures. Thanks again,
Because of time constraints, we are unable to post all of the marvelous submissions that come our way. Many letters we don’t even have time to read. We are thrilled to posty your photos of a Royal Walnut Moth laying eggs and the resulting hatching of Hickory Horned Devils.
Letter 15 – The Devil's are Arriving!!! Hickory Horned Devil
Name that Bug
Hi! I found your site while web searching for the identity of this little critter. He’s easily 5 inches long and we found him in the back yard in eastern PA near NewHope getting ready for a family picnic. I’ll send you a second picture of the full bug.
We have been waiting for the photos of the Hickory Horned Devils, caterpillars of the Royal Walnut Moth, Citheronia regalis, to arrive. This is America’s largest caterpillar, and although fierce looking, it is harmless. It feeds on the leaves of trees like Walnut, Hickory and Persimmon. In the fall, the caterpillar leaves the tops of the trees and climbs to the ground where it will dig and pupate, emerging as an adult moth in the spring. We hope you are releasing your captive.
Letter 16 – Royal Walnut Moth
Location: Philadelphia, Pennsylvania
August 30, 2010 1:35 pm
Can you please identify this bug? It was hanging out on the back of a co-worker’s car in late July.
We cannot imagine how you ever managed to contain yourself for over a month by suppressing your curiosity regarding the identity of this Royal Walnut Moth or Regal Moth, the adult form of the fantastic Hickory Horned Devil caterpillar.
Letter 17 – Royal Walnut Moth
What bug is this?
Location: Philadelphia area
July 3, 2011 12:37 pm
We have a large organge bug with wings and antennas on our front door. Can you help us identify it? I’ve attached a photo.
This gorgeous moth is a Royal Walnut Moth or Regal Moth, and it is the adult form of the equally spectacular Hickory Horned Devil caterpillar.
Letter 18 – Royal Walnut Moth
vibrant red/orange moth in Central Virginia
Location: Central Virginia
July 5, 2011 4:18 pm
Hey bugman, spotted this beauty in the drive through at Burger King. What kind of moth is it? Are they common for Virginia?
This is a Royal Walnut Moth and they are not uncommon.
Thanks Daniel, some folks over at Reddit also found it for me. Since growing older I have forgotten how numerous the many wonders of this earth are, there were so many different moths that I could not ID it very quickly online
Letter 19 – Royal Walnut Moth
Location: Western Pennsylvania
July 13, 2011 2:24 am
This bug was outside of my work place. I saw one similar to this last year in the same spot. What is this? It’s so weird!
Your moth is a Royal Walnut Moth, the adult of the fierce looking, but harmless, Hickory Horned Devil caterpillar.
Letter 20 – Royal Walnut Moth
is this moth poisonous
July 22, 2011 12:21 am
It looked like it had a stinger
Your moth is a Royal Walnut Moth and it does not have a stinger and it is not poisonous. We find it interesting that you would suppose that it is a venomous species upon seeing the adult, because it is the fearsome looking caterpillar, the Hickory Horned Devil, that generally elicits such a supposition. The frightfully spiny Hickory Horned Devil is also perfectly harmless.
Letter 21 – Royal Walnut Moth
Royal Walnut Moth
July 22, 2011 3:47 pm
Just wanted to add this picture i took.
Thanks for adding to our archive of Royal Walnut Moth sightings this year.
Letter 22 – Royal Walnut Moth
Large Red/Orange & white striped moth or butterfly?
Location: Conover, NC Jack-in-the-Box
August 13, 2011 2:13 am
I have spent hours looking to identify this big guy. I came out the door, saw him & was mesmerized (I love moths & butterflies). He stayed still long enough for me to measure & photograph him. His body length was approx. 3 1/4” long. His wings were partially closed, but I guess up to 5”. Can you help me identify him, please? Thank you for any help you can provide.
Signature: Ginger in NC
Letter 23 – Royal Walnut Moth
Subject: new or endangered bug
Location: baltimore, md.
June 22, 2012 2:25 pm
Hey bugman, i was just around Baltimore, md. At a campground, and i saw this bug. Ive never seen anything like it before so i took a few pictures.
Its a very bright orange and white bug about 2.5 + inches in length.
I was wondering if u could identify it.
Signature: thanks, frankie
This beautiful moth is a Royal Walnut Moth or Regal Moth.
Letter 24 – Royal Walnut Moth
Subject: Unknown moth of some sort?
Location: Birmingham, AL
June 26, 2012 12:37 pm
My husband came across this bug at his place of work, which is in Birmingham, AL. Never seen one like it before. It didn’t move or fly away while he took a picture, so not sure of specifics outside of how it looks. I’m guessing it’s some sort of moth, but it’s so strange-looking, I’d love to know more about it.
Signature: Jennifer Quakenbuh
This beautiful moth is known as the Royal Walnut Moth or Regal Moth. The caterpillar is the fierce looking but harmless Hickory Horned Devil. Each year in late June and July, we get reports of the adult moth and the caterpillar sightings seem to peak in September. Caterpillars feed on the leaves of walnut, hickory and other trees, including ash, burning bush, butternut, cotton, gum, lilac, pecan, persimmon, sumac and sycamore according to BugGuide. Adults do not feed.
Letter 25 – Royal Walnut Moth
Subject: Is this a moth?
Location: Northern KY
July 16, 2013 6:23 am
Hi, my daughter in law sent me a photo of a bug they found at her work and I have never seen anything like this. I almost thought it was fake. Thanks
Signature: Brenda Updike
This impressive moth is a Royal Walnut Moth, a species that only lives a few days as an adult, and it does not eat. Royal Walnut Moths live long enough to mate and reproduce, and they develop from the equally impressive caterpillar known as the Hickory Horned Devil.
Letter 26 – Royal Walnut Moth
Subject: Is this an Imperial Moth or something else?
Location: Bear, Delaware
July 17, 2013 10:46 am
So, I found this rather large moth just outside of my front door this afternoon and was wondering if I could get it identified? I live in the Bear, Delaware area if that helps any. I’ve only got one picture because it’s in a bit of an awkward location, but hopefully it’s enough.
Signature: Stephen Miller
This impressive moth is a Royal Walnut Moth. Just yesterday we just posted our first submission of a Royal Walnut Moth this year.
Letter 27 – Royal Walnut Moth
Subject: What’s this moth?
Location: Cherokee, NC
August 2, 2014 11:35 pm
Hi! While visiting Cherokee, NC I found this guy on the side of an ice cream shop. I love the colors and markings. I went through several pages on your site and will continue, but would love for you to identify it for me. A friend posted a pic of the same kind found in Atlanta, GA.
Signature: T Benefield
Dear T Benefield,
This beautiful moth is known as a Royal Walnut Moth or Regal Moth, and this is but our second report this year. Most years, we receive identification requests and submissions in June or July, though BugGuide does state: “Adults fly from late May to September.” Like other Giant Silk Moths in the family Saturniidae, the Royal Walnut Moth does not feed as an adult, and most individuals live about a week, long enough to mate and lay eggs.
Letter 28 – Royal Walnut Moth
Subject: Large unidentified moth
Location: Greenville, SC, USA
August 3, 2014 8:19 am
Hi there! I spotted a moth this morning I’ve never seen before. It’s about 5 inches long from head to tip of the abdomen. It was found on August 3rd, 2014. It was active the night before, probably attracted by the lights on the porch, and was resting this morning. The pictures I’ve taken are it next to a pack of 100s cigarettes (little larger than your average pack) and a standard sized outdoor outlet (which has been taped to prevent roaches from getting in).
We just posted another image of a Royal Walnut Moth, and that one was from North Carolina. We are surprised that they seem to be appearing much later this year. We generally get reports in June and July, though BugGuide does indicate that adults fly from May through September.
Letter 29 – Royal Walnut Moth
Subject: Royal Walnut Moth
Location: Lebanon, Tennessee
May 17, 2017 12:52 pm
Here is a Royal Walnut Moth I found this morning on our sidewalk in Lebanon, Tenessee.
Signature: Donna Samuels
We wish you had had the opportunity to see this gorgeous Royal Walnut Moth while it was still living.
Letter 30 – Royal Walnut Moth
Subject: moth identification
Location: Franklin Ky
June 29, 2017 3:42 pm
Saw this moth on the outside wall of a Pilot gas station in Franklin, Kentucky. On June 29, 2017. What kind is it, it’s beautiful!
Signature: R. Orcutt
Letter 31 – Royal Walnut Moth
Subject: Orange moth
Geographic location of the bug: Western North Carolina
Time: 08:21 AM EDT
Your letter to the bugman: Each summer we get plenty of moths, especially the Luna’s,but this is the first time in 31 years of living on our mountain that I’ve seen THIS guy! What the heck is he?
How you want your letter signed: Jessica
This is our first posting this year of a Royal Walnut Moth. Often beautiful moths and butterflies develop from nondescript caterpillars, but this is not the case of the Royal Walnut Moth, which begins life as a spectacular Hickory Horned Devil.
Letter 32 – Royal Walnut Moth
Geographic location of the bug: Shepherdstown, WV
Time: 12:38 PM EDT
Your letter to the bugman: Found him in the rocks
How you want your letter signed: Todd Fagan
This gorgeous moth is a Royal Walnut Moth.