Overview
The Hickory Horned Devil is the sensational, monstrous-looking larval form of the Regal Moth (Citheronia regalis). Ranking among the largest, heaviest caterpillars in North America, this gentle giant commands immediate awe with its vibrant turquoise-green body and frightening crown of curving, orange-and-black spiny horns. Despite its ferocious, dragon-like appearance designed to terrify avian predators, the caterpillar is completely harmless, lacking any stinging spines or defensive venom.
Biology and Physical Characteristics
Reaching an astounding length of up to six inches, a mature fifth-instar Hickory Horned Devil develops a cylindrical turquoise-green to aqua body banded with bold black spiracular markings. Behind its head rise four pairs of elongated, backward-curving scoli resembling devilish horns that measure up to three-quarters of an inch in length. When fully grown, it burrows underground to pupate directly in the soil without spinning a cocoon, emerging the following summer as the colossal, orange-and-slate Regal Moth.
Behavior and Ecology
Feeding voraciously in high forest canopies during late summer, the caterpillar consumes the foliage of hickory, walnut, pecan, sweetgum, and persimmon trees. When threatened by insectivorous birds, it thrashes its head and horned thorax violently from side to side, emitting an audible clicking sound to deter predators. After descending tree trunks in late summer, it wanders conspicuously across forest floors to locate suitable burrowing soil.
Conservation and Human Impact
Classified as secure across its core southern range, Citheronia regalis has experienced localized declines and extirpations in the northeastern United States. Factors include widespread aerial pesticide spraying against spongy moths, suburban habitat fragmentation, and light pollution that disrupts nocturnal mating flights of adult moths. It is widely celebrated by entomologists and environmental educators as a harmless wonder of North American biodiversity.
Interesting Factoid
Despite its terrifying dragon-like horns and ferocious thrashing display, the Hickory Horned Devil is completely harmless and cannot sting, bite, or poison humans or animals.
Last updated: October 2026