The largest caterpillar in East Texas is the hickory horned devil, named after it’s looks; like a small dragon. The adult moth that emerges is a regal moth or royal walnut moth, Citheronia regalis. If you come across it unexpectedly, it can be very intimidating.
Despite its scary appearance, the hickory horned devil is completely harmless. A full-grown larva may be five inches long and as big around as your thumb. The caterpillar’s green body is armed with large, black spines along its back and four stout, black and yellow curved horns just behind its orange head.
Life cycle
The caterpillar feeds on a variety of hardwood trees including hickory, walnut, persimmon, sweetgum, sycamore, and ash. It can consume a considerable amount of foliage. But because the adult moth lays her eggs singly among several trees or host plants, the caterpillar doesn’t cause any significant damage.
You will likely find hickory horned devils in Oct. as the caterpillar matures. When the caterpillar is fully grown, it will crawl down the tree to pupate in the soil. It does not spin a cocoon but forms a large naked pupa that is dark brown to black, over two inches long, and almost an inch in diameter. The tail is pointed, and the head is rounded. The pupa will remain in the soil through the winter and the adult moth will emerge in early summer.
The regal moth is the adult of the hickory horned devil. This moth may have a wingspan of six inches and can be found in early summer in East Texas.
Hickory horned devils are easily reared to the adult moth stage. If a caterpillar is found still feeding on the host plant, place the caterpillar, along with some host plant foliage, in a large container (one-to-two-gallon size). Each day, fresh foliage should be provided for the caterpillar. Two or three inches of loose, moist soil in the bottom of the container provides a suitable place to pupate when the time comes.
If the caterpillar is found on the ground, chances are it has completed feeding and is searching for a place to pupate. In this case, place the caterpillar in a container with soil (as described above) and before long it will probably change to a pupa. If kept indoors, a beautiful regal moth may emerge during the winter.
Sometimes the hickory horned devil will be attacked by a parasitic wasp or fly. Since the larva of the wasp or fly feeds inside the body of the caterpillar, it is usually not obvious that the caterpillar has been parasitized. A parasitized caterpillar may pupate, but rarely survives to become an adult moth.