Humphrey the Caterpillar

Humphrey - Hickory Horned Devil Caterpillar
(Picture by Linda Secrist)

One of the cool things about working on the hotline, is the occasional surprise when a bug, or plant sample comes in, that is out of the ordinary.  I watched Steve get all excited last year when an example of Dodder, a parasitic weed, was brought in.  We learn about this stuff from books, and our MG classes, but it's rare enough, that Steve, in all his years in the Horticulture industry, had never seen a live sample, outside a classroom.

Citheronia regalis
(Picture by Linda Secrist)

The same thing happened this week with a huge, 5+ inch caterpillar, with a cigar-size girth, that was promptly named Humphrey by Barb Petrucci's granddaughter, Kenzie, in helping Barb that day.  Linda Secrist helped identify Humphrey as a Hickory Horned Devil, or Citheronia regalis.

The species overwinters as a pupa in the ground.
The larva, commonly called the hickory horned devil, is one of the largest found in the area. The full-grown caterpillar (Photo 1) is 100-125 mm long. The head is orange and the body bluish green or sometimes brownish. Useful distinguishing structures are the long conspicuous spines or horns on the thorax; there are two on the first thoracic segment and four on each of the second and third segments. Thoracic horns are usually orange tipped with black, but sometimes may be mostly black. Rows of short black spines occur along the back and sides of the body.

Caterpillars are generally present from July through September. When fully grown, larvae enter the soil and pupate.

Citheronia regalis
(Picture by Linda Secrist)

Another common name is the Royal Walnut Moth.  Humphrey was Dr. Raupp's "Bug of the Week" September 21, 2009.

Adults do not feed and live only a few short days, but caterpillars require several weeks to develop. The hickory horned devil occurs from Florida to New England.  In Southern states, two generations of this beauty occur each year and in the north, only one generation completes development each year.

The royal or regal moths and the giant silk moths like Nancy's earlier Polyphemus moth, belong to the same family Saturniidae.

Most members of this family are large moths, the cecropia being the largest moth in North America. Because of their large size and sometimes striking colors and shapes, they attract a lot of attention when they are encountered, even among people who have no special interest in entomology. Also because the moths are rarely abundant, they are hardly ever taken for granted when one announces its presence by fluttering against a window at night.

The caterpillar stages of these moths are also large and spectacular and are observed more often than the moths. Some are ornamented with spines and barbed horns which makes them seem likely candidates for roles in horror movies. For the most part, this horrendous appearance is all show as far as harm to humans is concerned. However, the spines on the io moth caterpillar are true defensive weapons and can produce a painful sting to anyone who carelessly handles them.

Adult Citheronia regalis - Clemson University

The adult moth emerges in late June to early July and has a wingspread of six inches.  The body is orange. The front wings are grayish with red-orange veins and yellow spots; hind wings are mostly orange with some yellow markings.