The very large caterpillar in your photo is called the hickory horned devil. It is the caterpillar stage of the regal moth or royal walnut moth, Citheronia regalis (Order: Lepidoptera, Family: Saturniidae). These caterpillars are among the largest found in North America. They are found throughout the eastern U.S., but are more common in the southern states. The caterpillars feed on hickory, walnut, pecan, butternut and similar plants in the walnut family, but can also feed on a variety of other tress and shrubs as well. They are not considered pests, and are harmless, although if you were to pick one up, you might get "poked" by the impressive horns on the front end of the body, which the caterpillar uses in defense. If you search the internet for hickory horned devil, you will find more information and photos of both the caterpillars and adult moths of this fascinating insect.

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