Wednesday, September 4, 2013

Hickory Horned Devil

If you've ever seen one of these amazing caterpillars, you will never forget it.  At a whopping 12.5-14 cm (about 5-6 inches) long, with its weird looking black-tipped reddish "horns" and thorny-looking black spikes on its plump greenish body, it's definitely a sight to remember!  This caterpillar called a "hickory horned devil" is the larval form of the royal walnut moth also known as a regal moth (Citheronia regalis) native to deciduous forests of the Eastern United States.  It's a Saturniid moth, a family of moths consisting of giant silk moths and royal moths--examples you might be familiar with include the luna moth, cecropia moth, and polyphemus moth.  Many thanks to Judy Molnar and Lu Ackley for setting me up with this beautiful creature so I could get photos.  Many, many thanks to my friend and photography mentor, Don Redmond for loaning me a lot of studio lighting equipment so I could get these shots!  I'll start with some full body shots:
It eats a variety of leaves including sweetgum, hickory, persimmon, and winged sumac to name a few.  Here, it's chowing down on a sweetgum leaf.  Notice the first three pairs of legs--they are the true legs:
Normally if you see something this "spiky" you should not touch it.  Things with bright colors and spikes are Nature's way of saying "do not touch"--the animal may be poisonous or have venomous spines.  Ironically, this caterpillar does not have venomous spines!  It does, however, have a defense--when touched in the middle of its back, both ends will whip together towards the center--I suppose if you were a bird trying catch it, you'd be very surprised indeed!  Here's a close-up of the "horns" on its head :
Detail of the head--see the two stubby antennae on either side of the mouth?  It's "eyes" are the clusters of dots to the sides near the base of the antennae:
The prolegs will disappear when the caterpillar pupates--only the front three pair of legs closest to the head are the true legs (they look "spiky" compared to the prolegs that look "squishy.")
The back end of the caterpillar is sort of armor-plated.  The top brownish triangle is the anal plate and the back prolegs are also "armored."  The whole back end is meant to fake out predators by looking like its head:
A close up of the big spike on the back end--although it appears rigid, it's somewhat flexible:
And finally (don't freak out...) here's its "frass" or poop:
The caterpillar will go through five "instars" (a growth period followed by a shedding of its skin) before it pupates.  However, the hickory horned devil does not spin a cocoon like most moths--instead it will burrow into the ground to pupate where its skin will harden and turn a dark brownish-black color.  It'll overwinter until the following summer--usually during a period of sustained warmth and humidity.
More in two weeks!

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