Currently viewing the category: "Hickory Horned Devil"
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LARGE Caterpillar found in Ozark, Missouri
Location: Ozark, MO (southwest Missouri)
July 21, 2011 10:39 pm
Can you identify this large dark/bronze/copper/brown colored caterpillar? We found it in early July in my flower bed, not far from my Walnut tree. It was about 3 inches long. We saw no others before or since. I’ve lived here 12 years and have never seen such a creature! In the photos, you can see the ”horns” and the tufts of ”hair”. It has a black ”band” across it’s head. Also, what Moth or Butterfly will it become?
Signature: ~Susi M.

Hickory Horned Devil

Hi Susi,
Your large caterpillar, a Hickory Horned Devil, will nearly double in size and change color from brown to aqua-green as it progresses through metamorphosis to become the largest North American Caterpillar.  We received our first Hickory Horned Devil sighting of 2011 a few weeks back and we have been getting numerous reports of the adult Royal Walnut Moths this summer, which makes us believe that there will be even more mature caterpillar sightings in August and September.  Folks don’t usually notice the Hickory Horned Devil until the caterpillars have grown to full size and  then climb from the trees to crawl upon the ground in search of a suitable location to dig beneath the surface where pupation occurs.  Walnut and Hickory, which provide the common names for the moth and its caterpillar, are just a few of the trees that serve as a host for the caterpillar.  Others include sumac and persimmon.  The adult Royal Walnut Moth, like other Giant Silk Moths, does not feed as an adult.  Adults live long enough to mate and lay eggs.  BugGuide has a nice series of images of various instars of the Hickory Horned Devil.  The fully grown caterpillar with its bright coloration and striking horns is often likened to a Chinese dragon.

Daniel,
Thank you SO much for replying so QUICKLY!! We found a very large moth last night fluttering against a rock wall here, put it in a jar and by morning it had laid numerous eggs! We think it may be the Royal Walnut Moth from our Hickory Horned Devil Caterpillar you identified! I will take photos and send them to you to be sure. It doesn’t look exactly like the other Royal Walnut Moths I’ve seen photos of at the Bug Guide link you sent me, but it may be one of them. I’ve lived here many years and have never seen these caterpillars near any walnut trees in this area. Where are they normally from? And why would they be appearing here all of a sudden? Thanks again.
~Susi Meredith
Ozark, Missouri

Hi again Susi,
Just because you didn’t notice any Hickory Horned Devils does not mean they were not present.  Even though they are large, they could easily escape notice in a large tree.  Since the adult moths fly, they are capable of increasing their range to places where there is available food.  Perhaps you are part of a natural range expansion.

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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.

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Caterpillar emergence
Location: Pittsburgh, PA
May 15, 2011 9:35 am
I need to know the emergence dates of the following moth species. They have been stored in my garage since last fall. All but the Polyphemus were hand-reared. I live in Pittsburgh, PA. The moths are Promethea, Royal Walnut and Polyphemus. Thanks!
Signature: June

Hickory Horned Devil: early instar

Dear June,
We don’t believe we can predict with accuracy the exact emergence dates for the Giant Silkmoths you have listed because emergence is not something that can be calculated by counting days, weeks or months.  Temperature and other climactic conditions are significant factors.  However, we can use historical sighting information on adults of the species to try to predict emergence dates.  Since Giant Silkmoths don’t feed as adults, their average longevity would be about a week, during which time they mate and reproduce, if they are lucky, though many individuals provide food for other creatures and never manage to mate.  One of our favorite yearly activities involves tracking the northern emergence patterns of the Luna Moth which began in Texas in late February this year.  Our most northern reports thus far this year have been from Virginia and Iowa, and we expect to begin hearing from Main and possibly Canada by late May or early June.  Later in the year, reports of a second brood will come again from the southernmost portions of the range in Texas and Florida
We don’t really track the other Giant Silkmoths the way we do the Luna Moth.  Starting with the Promethea Moth, according to BugGuide:  “One brooad flies June to July northward. Two broods southward, flying March to May and July to August.”  The data page on BugGuide with information on sighting in specific states has sightings in March, June and July in Ohio and May and July in Pennsylvania.  The March sighting might have been a cocoon since various stages of the metamorphosis are not aggregated in the data presentation.  We would predict a June hatching for your moths.  Regarding the Royal Walnut Moth or Regal Moth, the adult of the Hickory Horned Devil you have provided as an illustration, BugGuide indicates:  “Adults fly from late May to September” however, that is information spread out over the entire range.    The data page on the Regal Moth on BugGuide indicates sightings from June through September in Pennsylvania and July and August for Ohio, but that information would include adults and caterpillars, and we always get Hickory Horned Devil sightings in September.  Our best guess is that you can expect emergence of the Royal Walnut Moth from the pupa in June, or possibly as late as July.  Regarding the Polyphemus Moth, BugGuide indicates:  “In southern United States, adults fly April-May and July-August (2 broods); in northern part of range, adults fly from May to July (1 brood).”  According to the data page, sightings in Ohio run March to September exempting May and those for Pennsylvania are from May to August.  Based on that information, we might expect your Polyphemus Moths to hatch the soonest, possibly beginning now and into June.

Thanks, Daniel!  I have been successful in the past with the Promethea as far as mating and collecting eggs.  I would like to try the same with the other moth species.  I’m thinking it might be best for me to attach the cocoons to the inside of the metal hardware cloth cage that I have used for the Promethea and wait to see when each emerges.
Thanks for your efforts in researching my questions.  I appreciate it very much.
June

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Horny Caterpillar?
Location: Ohio
February 10, 2011 8:13 am
This bug was found inside the house, under the bed covers! Friends are laughingly calling it the ”horny caterpillar” … can you enlighten us please?
Signature: photogirl800mm

Hickory Horned Devil

Hi photogirl800mm,
Awesome.  This is a Hickory Horned Devil, the larva of the Royal Walnut Moth, and it is the largest Caterpillar in North America.  Your letter did not indicate if this was a recent discovery (which we doubt) or if it was found in bed last autumn.  We did not get as many submissions of Hickory Horned Devils this past season as we have in years past.

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Square Eyed Hornworm
May 29, 2010
Found this amazing and ugly fellow on a Vitex agnus-castus nibbling away. He was up high in the tree and I only saw one. It is May in Wharton, Texas. He is between 3 1/2″ and 4″ long. I haven’t a clue. I wish I was a better photographer. My neighbor took some pictures – if I get them (and they should be better) I will send them on. I looked through all of your hornworms and didn’t see him, but then again, maybe he isn’t a hornworm. Thanks so much for this site. I have used it sooooo many times.
Carolyn
Wharton, Texas

Hickory Horned Devil

Hi Carolyn,
This is extremely early in the year for us to receive a photo of a Hickory Horned Devil, the caterpillar of the Royal Walnut Moth.  Typically, we get the first Hickory Horned Devil photos around August.  The Hickory Horned Devil is not a Hornworm, but a rather one of the Silkworm Moths.

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Damselfly or not?
October 13, 2009
I found this bug at my grandma’s house. At first I thought he was a dragonfly. He’s brown and has multiple wings. My mom thinks he is a damselfly. Can you help us? also, I am sending 2 pictures of a garden spider and Hickory Horned Devil.
Thanks!
Scarlett
McAlpin, Florida

Hickory Horned Devil

Hickory Horned Devil

Hi Scarlett,
We already wrote back to you to tell you that the damselfly is actually an Antlion.  In trying to select letters for posting today, we would much rather post your photo of the Hickory Horned Devil since we did not receive as many nice photos of this spectacular caterpillar as we have in past years.

What's That Bug? does not endorse extermination