Hickory Horned Devil Caterpillar Facts: Unveiling Nature’s Strangest Critters

The hickory horned devil caterpillar is a fascinating and unique creature in the world of insects. As the largest caterpillar in North America, it can grow up to six inches in length, making it an interesting subject for nature enthusiasts. The hickory horned devil is the larva of the regal moth and feeds on various types of trees like walnut, hickory, pecan, persimmon, and sweet gum trees.

Despite its intimidating appearance with large, curved horns and vibrant colors, the hickory horned devil caterpillar is actually harmless to humans. Its transformation into the regal moth is equally impressive, with the adult moth being nocturnal and displaying eye-catching patterns and colors.

In this article, we will explore fascinating facts about the hickory horned devil caterpillar, including its life cycle, habitat, and unique features, as well as its benefits to the ecosystem. So, let’s delve into the wonderful world of this intriguing insect.

Hickory Horned Devil Caterpillar: An Overview

Physical Appearance

The Hickory Horned Devil Caterpillar is known for its unique and intimidating appearance. This caterpillar is predominantly green with a mix of black, yellow, and orange colors. Its most striking features include:

  • Large size, growing up to 5 inches long
  • Paired rows of black spines on its back
  • Yellow to orange curved horns just behind the head

Life Cycle

The Hickory Horned Devil’s life cycle has four stages: egg, caterpillar, cocoon, and adult moth. The stages can be summarized as follows:

  • Eggs: Regal moth lays hundreds of eggs
  • Caterpillar: Grows and molts several times, reaching max size
  • Cocoon: Forms a brown pupa within a silk cocoon
  • Adult moth: Transforms into a large regal moth

Behavior

Some key behaviors of the Hickory Horned Devil Caterpillar

Citheronia Regalis: The Regal Moth

Physical Characteristics

  • The hickory horned devil (Citheronia regalis) is the largest caterpillar in North America.
  • It starts as a tiny caterpillar and grows to a mature size of around 12.5 to 14 cm in length.

For the adult regal moth, their body is orange with narrow yellow banding 1. One unique feature in their appearance is their furry body. Here’s a quick comparison between male and female regal moths:

Feature Male Regal Moth Female Regal Moth
Pattern and color Same as female Gray, tan, or slightly olive
Wings size and shape Smaller and narrower wings Bigger wings

Wings and Wingspan

The regal moth is characterized by its distinct wings. Their forewings are gray, tan, or slightly olive with orange or reddish-orange veins and pale yellow spots. On the other hand, their hindwings are more orange, usually with a yellow patch at the base 2.

Range and Distribution

The native range of the regal moth extends across much of the eastern half of the United States, including Texas and the Midwest. However, they are more commonly found in the southern parts of the country. The hickory horned devil commonly feeds on the leaves of various trees such as:

  • Walnut
  • Hickory
  • Pecan
  • Persimmon
  • Sweet gum 3

Feeding and Host Plants

Primary Host Plants

Hickory horned devil caterpillars primarily feed on the leaves of different hickory-type trees, such as walnut, hickory, and pecan, among others. These trees are their main source of sustenance.

Secondary Host Plants

Besides the primary host plants, hickory horned devil caterpillars also consume leaves of some secondary host plants, such as persimmon, sweet gum, and sumac trees. They rely on these secondary host plants when their main food sources aren’t available.

Larval Diet

When hickory horned devil caterpillars hatch, they begin their life by eating the leaves of their host plants. As they grow, they continue to feed on the foliage of their preferred trees, which largely include those in the Carya (hickory) and Juglans (walnut) families.

Comparison Table

Host Plant Type Examples Caterpillar Preference
Primary Hickory, Walnut, Pecan Most Preferred
Secondary Persimmon, Sweet Gum, Sumac Less Preferred

Key Features of Hickory Horned Devil Caterpillars:

  • Largest caterpillar in North America
  • Appear fierce but are harmless
  • Primary diet consists of leaves from hickory-type trees
  • Can also feed on secondary host plants when necessary

Characteristics of Primary Host Plants:

  • Belong to Carya and Juglans families
  • Include hickory, walnut, and pecan trees

Characteristics of Secondary Host Plants:

  • Include persimmon, sweet gum, and sumac trees
  • Utilized when primary host plants are scarce or unavailable

Life Stages and Reproduction

Eggs

  • Female regal moths lay hundreds of eggs on host plants, such as hickory and walnut trees.
  • Eggs are small, round, and light green or yellow in color.

Larvae

  • Hickory horned devil is the largest caterpillar in the United States, reaching up to 14 cm in length.
  • Larvae feed on leaves of various trees like walnut, hickory, pecan, persimmon, and sweet gum.
  • They have a striking appearance, with orange, black, and blue coloration, and long spiky projections on their heads.

Pupation and Cocoon

  • Mature larvae pupate in soil – they burrow into the ground and create a protective cocoon.
  • Pupa is reddish-brown in color and encased within a silk cocoon.

Adults and Mating

  • Adult regal moths emerge from their cocoons during summer months.
  • They have a wingspan of 9.5-15.5 cm and an orange body with narrow yellow banding.
  • Adults are nocturnal and are attracted to lighting fixtures.
  • Mating occurs shortly after emergence, and adults communicate with each other through the use of pheromones.
Area Common Presence Host Plants
Florida Yes Hickory, walnut, pecan, persimmon, sweet gum
Central Florida Yes Hickory, walnut, pecan, persimmon, sweet gum
Texas Yes Hickory, walnut, pecan, persimmon, sweet gum
Other United States Less common, but present Hickory, walnut, pecan, persimmon, sweet gum

Pros and Cons of Hickory Horned Devil Caterpillars

Pros:

  • Caterpillars are harmless to humans and pets.
  • They help in natural pest control by preying on other insects.

Cons:

  • They can cause defoliation of host trees.
  • Large infestations can be a concern for tree health.

Habitats and Distribution

Geographical Range

The hickory horned devil caterpillar, or Citheronia regalis, can be found throughout the eastern United States. Its range spans from New Jersey and Massachusetts in the north, down to East Texas in the south.

Preferred Habitats

These caterpillars primarily inhabit deciduous forests, where they feed on the leaves of trees such as walnut, hickory, pecan, persimmon, and sweet gum1. Here’s a list of their preferred habitats:

  • Deciduous forests
  • Walnut, hickory, and pecan trees
  • Persimmon and sweet gum trees

Comparison Table

Caterpillar Region Habitat Primary Food Source
Hickory Horned Devil Eastern US Deciduous forests Walnut, hickory, pecan, persimmon, and sweet gum trees

Conservation and Challenges

Threats and Decline

The hickory horned devil caterpillar, known for its harmless yet unusual appearance, faces a few challenges. Despite being harmless, their ferocious look can lead to them being eradicated by misinformed individuals. These caterpillars are essential for the ecosystem as they contribute to the diet of certain bird species. Their natural habitat mainly consists of walnut, hickory, pecan, persimmon, and sweet gum trees. A decline in these trees could pose a threat to their numbers.

Survival Techniques

Hickory horned devil caterpillars are equipped with various survival techniques. Their unique coloration, ranging from blue to turquoise, acts as a camouflage, helping them blend into their surroundings.

Burrowing

One of their most essential survival techniques involves burrowing into the soil or ground. This is where they spend their time during the overwinter stage, sheltering them from harsh weather and potential predators. They typically burrow during late October to mature into regal moths.

Diet and Adaptability

These caterpillars have an adaptive feeding nature, predominantly feeding on the following plants:

  • Rhus (Sumac)
  • Liquidambar styraciflua (Sweetgum)
  • Diospyros virginiana (Persimmon)

Adapting to different plants allows them to survive even if one food source becomes scarce. The ability to consume a variety of plants gives them an increased chance to survive potential habitat changes.

Habitat Threats Survival Technique Development Stage
Soil & Ground Habitat Destruction Burrowing October (Overwinter Stage)
Trees Misinformed Individuals Camouflage Larval Stage
Various Plants Food Scarcity Adaptability Larval Stage

Footnotes

  1. (https://entnemdept.ufl.edu/creatures/bfly/regal_moth.htm) 2

  2. (https://mdc.mo.gov/discover-nature/field-guide/regal-moth-royal-walnut-moth-hickory-horned-devil)

  3. (https://hgic.clemson.edu/what-is-it-wednesday-hickory-horned-devil-caterpillar/)

Reader Emails

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 – First Devil of the Season: Hickory Horned Devil

 

hhd
I noticed several instances of people reporting Royal Walnut Moths (including a Steve, a Stephanie, and another person from Louisville–what does this tell us?!). I stumbled across the larval form yesterday in Louisville.
Another Steve in Louisville

Hi Steve,
This is our first Hickory Horned Devil image this year, but we expect many more submissions come September.

Letter 2 – Hickory Horned Devil: Handful of Caterpillar!!!

 

hickory horned devil
My son,Tyler found this, I thought you might like the photo’s.
Thank You
Brian Marceaux
Vinton, LA.

Thanks for the image Brian. It is our first Hickory Horned Devil of the year.

Letter 3 – Bug of the Month: September 2006 – Hickory Horned Devil

 

hickory horned devils
Hi, Daniel and Lisa Anne,
Today at ~ 6:30 PM I took some pictures of the hickory horned devils (HHDs), three days after the last ones. I acquired a number of images, and am sending ten of them**. In a few of these pictures, a katydid (or so it appears) decided to have a chat with the hickory horned devils, but who knows what they said to each other. In one picture, I framed all three at once. They are still 4.5 ” long, and it surprises me that none of the three have been eaten by anything. Here they are: … Is it usual to see this many survive to adulthood from one batch of eggs? All I can say in defense of me sending y’all this many pictures is that you challenged me to do better! It would be interesting to me to see which ones you like, and don’t like. I enjoy nature photography and want to do it better. Best Regards,
Glenn

Hi Again Glenn,
We went for a classic pose that is, in our minds, a definitive Hickory Horned Devil, Citheronia regalis, image. We are pleased to use your excellent photograph as the Bug of the Month for September, the month we get the most letters requesting the identification of this impressive caterpillar.

Letter 4 – Hickory Horned Devil

 

I found this bug out in my yard this morning. It was near my tomato plants. It is a very odd looking thing. If you know what it is could you tell me if it is poisonous. It was thrashing around when I tried to pick it up. It reminded me of a snake. I have small dogs and was scared that they may try to eat it. They try to eat grub worms and I am afraid that they will make them sick. Thanks for your time.
Teresa Causey
Chavies, Kentucky

Dear Teresa,
I’m happy your photo arrived. We just received another siting from a young man who found one in his jeep, but there was no photo, only a verbal description. It is a Hicory Horned Devil, the largest North American caterpillar. It is the larva of the Royal (or Regal) Walnut Moth, Citheronia regalis. The forewings of the moth are olive colored with yellow spots and red veins. The hing wings are orange-red potted with yellow and the body is reddish brown with yellow bands. It is a beautiful moth. The caterpillars, though fearful in appearance, are harmless. They feed principally on Hickory, Walnut and Persimmon.
Ed. note: See next letter

Letter 5 – Black Widow captures bedraggled Regal Moth

 

Big moth and black widow
August 14, 2009
My son and I had a Discovery Channel moment leaving the post office yesterday. This moth was alive, and the spider was working very hard to wrap it up. It would climb up, drop a line down, throw a couple of legs over the moth, go over to the other wing, and repeat. The moth was fluttering but losing the battle.
We couldn’t believe this was right in the middle of the sidewalk (yes, there was a brick column in the *middle* of the sidewalk) at the entrance to a busy post office in the middle of the day!
I was going to take video but could only manage a quick cell phone photo before a well-meaning man came up and stomped the spider.
I think this is a real black widow, but I’m having trouble positively identifying the moth. We see them all the time here in Georgia – as the summer progresses, the moths get bigger.
Can you help?
Patty and Gabriel
Powder Springs, Georgia

Black Widow captures Regal Moth
Black Widow captures Regal Moth

Hi Patty and Gabriel,
We are sorry to hear that this shy and retiring, though poisonous Black Widow was stomped before getting to enjoy its gargantuan meal.  The moth is a very bedraggled Regal Moth or Royal Walnut Moth.  Its appearance indicates that it was already at the end of its short adult life.  Regal Moths do not feed as adults, and only fly long enough to mate and lay eggs, and possibly, like this specimen, provide a nutritious meal to a lucky predator.

Letter 6 – First Hickory Horned Devil of the season

 

What is this Caterpiller?
Location:  Central New Jersey, Howell Ironworks
August 14, 2010 5:28 am
Please help us find a name for this.
Frank & Dustin

Hickory Horned Devil

Hi Frank & Dustin,
We are excited to post your photo as it is our first posting of a Hickory Horned Devil, the caterpillar of the Royal Walnut Moth, that we are making this season.  This is generally regarded to be North America’s largest caterpillar.  Despite its fierce appearance, which has been compared to a Chinese dragon, it is perfectly harmless.

HI DANIEL
THANK YOU FOR IDENTIFING OUR FIND!!!
FRANK & DUSTIN ARACE

Letter 7 – First Hickory Horned Devil sighting of 2011

 

Scary Big horned catapillar…..
Location: NE Oklahoma
July 5, 2011 9:25 pm
Even the cats wouldn’t play with it. It made quite the conversation point during the 4th celebrations at the house. So much for fireworks!
Signature: Joe

HIckory Horned Devil

Hi Joe,
We are positively thrilled that you have supplied us with our first Hickory Horned Devil sighting of the year.  These are the largest caterpillars in North America and they are impressive creatures.  We also just posted two photos of the adult Royal Walnut Moth.  This mature caterpillar has left its food tree, often hickory or walnut, and it will burrow beneath the surface of the ground to pupate.  As an aside, though we love cats, they do not “play” with insects since the insects generally end up no faring so well.

Letter 8 – First Hickory Horned Devil sighting of 2012

 

Subject: Huge Green Caterpillar-like bug
Location: Windber pennsylvania
September 1, 2012 11:36 am
My friend found this huge bug! It resembles a caterpillar, but Ive never seen one w/ these characteristics or of this size! We live In Windber, PA-it is the end of Summer, Sept 1, but she found it yesterday-which was the end of August. It is the end of Summer here, so its been fairly hot.As you can see from the pictures-its green with spikes (black) on its back.
Signature: tammy

Hickory Horned Devil

Hi Tammy,
This Hickory Horned Devil is arguably the most spectacular North American caterpillar.  It is also considered the largest North American Caterpillar.  We love getting photos of Hickory Horned Devils toward the end of each summer.  The adult Royal Walnut Moth, which makes an appearance during the early part of summer, is also a spectacular looking insect.

Letter 9 – First Hickory Horned Devil of the season!!!

 

Subject: Angry Caterpillar/Worm
Location: Middletown, MD
August 26, 2013 6:33 am
Good morning!
My aunt took a picture of this caterpillar that she was attempting to rescue from the middle of a mid-Maryland road. Apparently it became quite aggressive, whipping around and shooting ”gunk” out of its sides. It’s hard to tell size from the pic, but she said it was as long as her hand from longest finger to wrist (and she has long hands). It also had horns all over its body. She said it was similar to the tomato eating caterpillars, but much larger and much more active/aggressive.
Signature: Thank you!! – chadrenne

Hickory Horned Devil
Hickory Horned Devil

Dear Chadrenne,
We always look forward to the first Hickory Horned Devil images of the year with mixed feelings as it is a signal of the end of summer.  The Hickory Horned Devil is likely the largest North American caterpillar, and despite its fearsome appearance and its aggressive behavior, it is perfectly harmless.  People have written comparing Hickory Horned Devils to Chinese dragons in the past, and that is a very understandable comparison.

Letter 10 – First Hickory Horned Devil posting of the season

 

Subject: Very hungry caterpillar
Location: Deltaville, VA (Tidewater)
July 16, 2015 8:38 am
At first we thought this caterpillar was a tomato or tobacco hornworm, but it was too spiky. We found it in an open field, mid-morning on a 75* day in July. The property is on the middle peninsula of Virginia. We’re surrounded by brackish water (Chesapeake bay watershed), but there are many farms (mostly corn) in the area.
Signature: Kelli

Hickory Horned Devil
Hickory Horned Devil

Dear Kelli,
Though there is no shortage on our site, we are thrilled to be able to create a new posting of the first Hickory Horned Devil of the year.  Each summer we get numerous identification requests for the largest, and arguably most distinctive looking North American caterpillar.  Despite its fierce appearance, the Hickory Horned Devil is perfectly harmless.  Hickory Horned Devils rarely leave the host trees (hickory, walnut and other trees) where they are feeding on leaves, but this large specimen is getting ready to pupate.  It will seek a location with favorable conditions and it will bury itself before metamorphosing into a naked pupa that will pass the winter with the adult Royal Walnut Moth emerging the following year. 

Hickory Horned Devil
Hickory Horned Devil

Letter 11 – Drawing of a large, colorful bug might be Regal Moth

 

Subject: Unknown bug
Location: Lubbock, tx
February 12, 2016 9:14 pm
Hello a few years ago I found this but crawling on my tree in my front yard. I was very creeped out so I ran in the house to get something to kill it and it was gone:( I don’t have a picture but I have a drawing of what It looks like. The bug was about 3-4 inches long
Signature: Carl J Young

Bug Drawing
Bug Drawing

Dear Carl,
As entomological identification drawings go, your example is lacking in critical details that would help us to identify what you observed, but we can deduce that it was very colorful, and by your description it is quite large.  Even though your drawing does not help us determine a classification, not many insects are large and colorful, but our first thoughts are that you saw either a moth, beetle, cicada or possibly a grasshopper.  Our first impression is that you might have seen a Regal Moth or Royal Walnut Moth, a species that is reported from Texas.  The Regal Moth is quite large, very colorful, and its markings are remarkably similar to your drawing.  Some other possibilities include the Eastern Hercules Beetle, which is the heaviest North American beetle, and it is found in Texas.  Annual Cicadas are quite large and they are found in Texas, and the Painted Grasshopper or Barber Pole Grasshopper is extremely colorful and found in Texas.

Letter 12 – First Hickory Horned Devil of 2017

 

Subject: What’s this caterpillar?
Location: Melrose Florida
August 19, 2017 10:10 am
Hello, I’m in Melrose Florida in a wooded area and came upon this guy on the trail. I’m curious what he is and since I can’t find a photo like him in my online searches thought you might appreciate this one. He’s about 4 inches long and 3/4 inch diameter. Beautiful creature and intimidating with all those spikes on his head.
Signature: Kimberly

Hickory Horned Devil

Dear Kimberly,
The Hickory Horned Devil is one of the largest and most impressive caterpillars in North America.  Though frightening looking, it is perfectly harmless, and those spikes are not capable of stinging.  This is our first Hickory Horned Devil sighting of the season.

Very cool! Thanks for the response. He was very beautiful!

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

6 thoughts on “Hickory Horned Devil Caterpillar Facts: Unveiling Nature’s Strangest Critters”

  1. Glad I found this website. My husband found this caterpillar in our driveway and had never seen one like this and didn’t know what it was. He gave it to our grandson to take to school to see if they could identify
    Thanks again for this site

    Reply
  2. Glad I found this website. My husband found this caterpillar in our driveway and had never seen one like this and didn’t know what it was. He gave it to our grandson to take to school to see if they could identify
    Thanks again for this site

    Reply
  3. I saw one of these this morning for the first time. I knew it wasn’t the tomato horn worm because of it’s bright red antenna and it’s size. It was huge. Glad I could find out what it is. Thank you for having a thorough website.

    Reply

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