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Imperial Moth Caterpillar - Eacles imperialis

Imperial Moth Caterpillar - Eacles imperialis
Ohio River Islands National Wildlife Refuge, West Virginia, USA
August 26, 2004
The closest I could come in Peterson's First Guides: Caterpillars was Imperial Moth. The one pictured was green and the text says they can also be tan or brown. How about orangish-red? Also, the field guide picture showed relatively short tubercules, while the one in my photo has horns almost like a Hickory Horned Devil. A variation in the instars, perhaps——bigger horns in the last instar?

What was the foodplant?
I wonder what drives the color? Foodplant? Time of year?

I raised a hickory horned devil and one of these on a backyard sweetgum this year and have a whole series of shots during the development. I look forward to posting those later on. It's interesting to see how the horns recede. They are quite long initially.

No Data :>(
Interesting idea— that maybe the chemicals of the tree host influence the coloration. I am sorry to say I neglected to record what kind of tree this fellow was on.

Seems like green would blend in best no matter what the food plant. Then again, with the spikes and the hairs, maybe they don't have to blend in.

Maybe they are like kittens and just come out differently in the genetic roulette!


Stephen Cresswell
Buckhannon, WV

Reddish Orange Phase
Yes, this is a Eacles imperialis larva. They occur in several color forms as you have seen called "phases," and will not change from one color phase to another. Florida's Fabulous Butterflies by Tom Emmel and Brian Kenney has the color form you have.

Alan, Thanks
Alan, Thanks very much, that is most helpful!


Stephen Cresswell
Buckhannon, WV

I don't know anything about caterpillars, but have you checked this web site?Eacles imperialis. It might be of help.

Thanks, Beatriz! The website
Thanks, Beatriz! The website showed that fifth instar Imperial Moth caterpillars don't have large horns, but third star do (not all instars were illustrated). Didn't see any that were this color...

That's a neat Moth gallery, with eggs, various instars, and pupae. Thanks for telling me about it!


Stephen Cresswell
Buckhannon, WV

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