Other Common Names
Royal Walnut Moth
Hickory Horned Devil (caterpillar)
Synonyms and other taxonomic changes
Citheronia regalis (Fabricius, 1793)
original combination Bombyx regalis Fabricius, 1793; Ent. Syst. 3 (1): 436
syn. Citheronia saengeri Neumoegen, 1891
syn. Citheronia infernalis Strecker, 1883
* phylogenetic sequence #224200
Common southward; rare northward. In some places it is listed as a threatened species.
Wingspan 95-155 mm; female larger than male
Caterpillar length to 140 mm
Adult: forewing gray with yellow spots and orange veins; hindwing mostly orange with yellow basal patch, and median patches at costa and inner margin
[description by Charles Covell (1)
Larva: body varies slightly in color, but is commonly blue-green; second and third thoracic segments each bear two long and two shorter orange "horns" with black tips; abdominal segments each have four short, black "horns", and segments 2 to 8 have a pale, oblique lateral stripe
[adapted from description at U. of Florida]
See also series of images beginning here, showing complete larval development:
Eastern United States: New York to Florida, west to Texas and Nebraska
Adults fly from late May to September.
Larvae usually seen from July to October while they are wandering on the ground searching for a suitable location to burrow into the soil for pupation.
Larvae feed on leaves of ash, burning bush, butternut, cotton, gum, hickory, lilac, pecan, persimmon, sumac, sycamore, and walnut.
Adults do not feed.
One generation per year. Eggs hatch 6-10 days after being laid, and the duration of the larval stage is about 35 days. Overwinters in pupa stage. Adults mate during the second evening after emergence and begin oviposition at dusk of the third evening.
This is one big caterpillar. One reference states that the full-size larva is "about the size of a large hot dog"! Although the caterpillar looks fierce, it is harmless.
Splendid Royal Moth
) has white on the wings and occurs only in southern Arizona and Mexico
Covell, plate 1 #18 (caterpillar), plate 9 #2 (imago). (1)
Tuskes, pp. 60-62, plate 1--caterpillar, plate 7--imago (2)
Ferguson, D. C., 1971. Moths of America North of Mexico, Fascicle 20.2a: p. 32; pl. 3.4, 14
Moth Photographers Group
- species page with photographs of live and pinned adults plus complete life cycle.
- live adult, larva, and pupa images by various photographers (forestryimages.org)
Univ. of Florida Featured Creatures.
- illustrated overview by Donald Hall and James Castner
Florida Nature account
live larva images by Emily Earp and Josh Hillman (floridanature.org)
Moth Photographers Group
- photographs of living Citheronia regalis
adults and related species.
Butterflies and Moths of North America
- photos of living and pinned adults plus overview, references, US distribution map.
Dalton State College
- pinned adult photos by James Adams, and live larva images by Hanna Roland.
Caterpillars of Eastern Forests, USGS
- live larva photos plus description, foodplants, seasonality (David Wagner and Valerie Giles)