Citheronia regalis

Adult male side view — Monroe County (Tracey Setze)

Adult female — Monroe County (Jim Horton)

Male antennae— Monroe County (Rick Malad)

Abdominal segments — Monroe County (Tracey Setze)

The third or fouth instar of the “Hickory Horned Devil” caterpillar — Brown County (Chris Kretvix)

The fifth instar of the “Hickory Horned Devil” caterpillar — Pike County (Jeremy Ross)

The “horns” of the “Hickory Horned Devil” caterpillar — Brown County (Kevin Wiener)

An Indiana Native

Citheronia regalis — Regal Moth

(Fabricius, 1773)

Hodges# 7706

Etymology

Citheronia: Presumably named for Cithaeron or Kithairon, a mountain range in Greece, which in Greek mythology, was sacred to the god Dionysus.

Regalis: Latin for “royal” or “pertaining to a king.”

Pronunciation

sith-ur-oh-nee-uh ree-gal-is

Other Common Names

Royal walnut moth. Also, the caterpillars are commonly called Hickory Horned Devils.

Adult Size and Description

Wingspan: 95–155 mm (3.7–6.1 in)
Coloration and Patterning:

Forewings gray to olive-gray, and hindwings reddish-brown.
Both sets of wings with bright reddish-orange scales covering the veins.
Each forewing contains numerous yellowish-white spots: two at the base, one in the discal area, and several others that comprise a broken-band postmedial line.

Sexual Dimorphism:

Females larger than males
Antennae quadripectinate on males and filiform on females

Defense Mechanisms:

Crypsis — Tree coloration

Range

This map illustrates documented North American records of Citheronia regalis as of 6 February 2021.

Documented record(s)

Conservation Status — NatureServe Rankings

Secure 5: Secure 4: Apparently secure NR: Not ranked

Notes: According to NatureServe, Citheronia regalis is “still doing well in most of its range, but extirpated or declining in a significant part, with expanding threat.” (NatureServe 2021). In years past, efforts to control the invasive gypsy moth (Lymantria dispar) included the use of DDT and the introduction of the parasitoid fly (Compsilura concinnata). These measures may have negatively impacted Citheronia regalis populations, and recent data indicates that Citheronia regalis is no longer extant in New England.

Floral Associates

Citheronia regalis caterpillars are the largest in Indiana. Polyphagous, they eat the foliage of several families and genera of native trees, including their namesake hickories (Carya spp.) Adults lack a digestive system, do not eat, and exist solely for reproduction.

Family	Taxonomic Name	Common Name
Known Larval Food Sources in Indiana
Order: Cornales
Cornaceae	Cornus spp.	dogwoods
Nyssaceae	Nyssa sylvatica	black gum, aka tupelo
Order: Dipsicales
Caprifoliaceae	Diervilla spp.	honeysuckles
Order: Ericales
Ebenaceae	Diospyros virginiana	persimmon
	Oxydendrum arboreum	sourwood
Order: Fagales
Betulaceae	Corylus americana	American hazelnut
Fagaceae	Quercus spp.	oaks
Juglandaceae	Carya spp.	hickories
	Juglans spp.	black walnut and butternut
Order: Gentianales
Rubiaceae	Cephalanthus occidentalis	buttonbush
Order: Hamamelidales
Platanaceae	Platanus occidentalis	American sycamore
Order: Lamiales
Oleaceae	Fraxinus spp.	ashes
	Syringa spp.	lilacs
Order: Laurales
Lauraceae	Sassafras albidum	sassafras
Order: Myrtales
Lythraceae	Lythrum spp.	loosestrifes
Order: Rosales
Rosaceae	Prunus spp.	cherries
Order: Salicales
Salicaceae	Salix spp.	willows
Order: Sapindales
Anacardiaceae	Rhus spp.	sumacs
Order: Saxifragales
Altingiaceae	Liquidambar styraciflua	American sweetgum

Regal Moth (Citheronia regalis) in Indiana

The map, graph(s), and data below represent the Indiana sightings of Citheronia regalis as of 21 December 2024, confirmed through photographic evidence by individuals who contributed to the Great American IN Nature Lepidoptera Project (GAIN LP).

Occurrences by County

Counties recorded: 16 of 92

Top counties/#of records:
Monroe: 16
Brown: 13
Jefferson: 8
Washington: 4
Putnam: 3
Switzerland: 2
Orange: 2

species present icon GAIN LP documented in county

Sightings by Month

Earliest live adult: Hannah Durham, Floyd County on 03 June 2015
Latest live adult observation: Suzanna Hendrix, Washington County on 20 September 2017

Total Sightings by Year

Total Number of observations (all years combined): 44
Number of field observers: 32

Sightings by Gender

Image Gallery

The images and records below were all submitted by individuals through the Great American Indiana Nature Lepidoptera Project (GAIN LP).

Additional Sources

NatureServe. 2021. Citheronia regalis Regal Walnut Moth. Explorer.natureserve.org. [accessed 2021 Feb 5]. https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.114866/Citheronia_regalis