Citheronia regalis - (Fabricius, 1793)
Regal Walnut Moth
Other English Common Names: Hickory Horned Devil, Regal Moth
Taxonomic Status: Accepted
Unique Identifier: ELEMENT_GLOBAL.2.114866
Element Code: IILEW0G010
Informal Taxonomy: Animals, Invertebrates - Insects - Butterflies and Moths - Giant Silkworm and Royal Moths
 
Kingdom Phylum Class Order Family Genus
Animalia Mandibulata Insecta Lepidoptera Saturniidae Citheronia
Genus Size: C - Small genus (6-20 species)
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Concept Reference
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Concept Reference: Tuskes, P. M., J. P. Tuttle, and M. M. Collins. 1996. The Wild Silk Moths of North America: A Natural History of the Saturniidae of the United States and Canada. Cornell University Press, Ithaca, New York. 250 pp.
Concept Reference Code: B96TUS01EHUS
Name Used in Concept Reference: Citheronia regalis
Conservation Status
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NatureServe Status

Global Status: G4G5
Global Status Last Reviewed: 06Dec2005
Global Status Last Changed: 21Jun2004
Rounded Global Status: G4 - Apparently Secure
Reasons: Still doing well in most of its range, but extirpated or declining in a significant part, with expanding threat. See threats and trend fields. Furhter decline is likely, range-wide collapse seems very unlikely.
Nation: United States
National Status: N4N5 (21Jun2004)
Nation: Canada
National Status: NNR

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Arkansas (SNR), Connecticut (SH), Illinois (SNR), Indiana (SNR), Maryland (S4), Massachusetts (SX), Michigan (SNR), New Jersey (S3), New York (S1), Pennsylvania (SU), Rhode Island (SX), Virginia (S4), West Virginia (SNR)
Canada British Columbia (SNR)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: Currently central New Jersey across southern Pennsylvania west through most or all of Indiana, much of Illinois half of Missouri south the extreme eastern Texas, the entire Gulf coast and central Florida. Until the 1950s also much of New York, most of southern New England, and most of Pennsylvania.

Area of Occupancy: 2,501 to >12,500 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 81 to >300
Number of Occurrences Comments: Still very widespread and in places common south of latitude 39 degrees, extirpated or nearly so north and east of South Jersey.

Population Size: 10,000 to >1,000,000 individuals

Overall Threat Impact: Medium
Overall Threat Impact Comments: Threats from biocides have probably abated somewhat but some impact is likely as Compsilura progresses westward and southward. Some Lepidopterists believe this and related species are vulnerable to artificial lighting, but there is no evidence and the species has recovered in some fairly developed parts of New Jersey.

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: There have been reports of decline in Ohio but little information--decline in northern parts of range does seem likely based on what happened in the Northeast. The species definitely recovered some in New Jersey and spread north to the central counties in the 1990s. Stable in most of range for now but possibly declining in small part.

Long-term Trend: Decline of <30% to increase of 25%
Long-term Trend Comments: Extirpated in several states, in most cases coinciding perfectly in time and space with past DDT spraying against gypsy moth. However there seems to be no doubt that the out of control gypsy moth biocontrol Compsilura concinnata was much more important and prevented recovery. This fly has spread over a much larger area since put does not always greatly reduce Saturniidae. If the regal moth has really collapsed in central Ohio, Compsilura would be athe almost certain cause. Stable in large area of Southeast at present and recovering in parts of New Jersey where it was very rare to (mostly) absent in the 1960s-1980s, but still overall sporadic and mostly uncommon to rare in that state. Probably declining somewhat overall with the spread of Compsilura but range-wide collapse is not expected..

Intrinsic Vulnerability: Moderately vulnerable

Other NatureServe Conservation Status Information

Protection Needs: Secure protection of extensive areas from Dimilin use. Bt will not affect this species as current formulations do not persist long enough.

Distribution
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Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) Currently central New Jersey across southern Pennsylvania west through most or all of Indiana, much of Illinois half of Missouri south the extreme eastern Texas, the entire Gulf coast and central Florida. Until the 1950s also much of New York, most of southern New England, and most of Pennsylvania.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.

Map unavailable!:
Distribution data for U.S. states and Canadian provinces is known to be incomplete or has not been reviewed for this taxon.
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AR, CT, IL, IN, MAextirpated, MD, MI, NJ, NY, PA, RIextirpated, VA, WV
Canada BC

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CT Litchfield (09005)*
MA Hampshire (25015)*
NJ Cape May (34009), Cumberland (34011)
PA Beaver (42007), Chester (42029), Greene (42059), Westmoreland (42129)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Middle Connecticut (01080201)+*, Housatonic (01100005)+*
02 Cohansey-Maurice (02040206)+, Lower Susquehanna (02050306)+
05 Kiskiminetas (05010008)+, Lower Monongahela (05020005)+, Upper Ohio (05030101)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: The Regal or Royal Walnut Moth
Habitat Type: Terrestrial
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Adult Food Habits: Nonfeeding
Food Comments: Caterpillar Hosts: Hickories (Carya), pecan (C. illinoensis), butternut (Juglans cinerea), black walnut (J. nigra), sweet gum (Liquidambar styraciflua), persimmon (Diospyros virginiana), sumacs (Rhus), cultivated cotton (Gossypium), and others. Adult Food: Adults do not feed (Lotts and Naberhaus 2017).
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation
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Group Name: Large Saturniidae

Use Class: Not applicable
Minimum Criteria for an Occurrence: A location where the species occurs where there is potential for continued occurrence or regular recurrence. Minimally an area where the species has been verified in some life stage based on a specimen or photograph in association with sufficient habitat to sustain a population. These are mostly unspecialized landscape level moths and few occurrences are really less than 500 hectares and many are almost undefinable.
An occurrence ranked higher than D should support a viable persistent population. These moths do not persist well once habitat becomes functionally fragmented. For example despite statements in Tuskees et al. (1996) CALLOSAMIA ANGULIFERA apparently no longer persists in scattered tulip tree stands in Massachusetts and Rhode Island but has in southern Connecticut where its foodplant is fairly common. As they note HYALOPHORA COLUMBIA COLUMBIA has died out following habitat fragmentation in many areas. Where documented occurrences are small (<500 hectares) if possible pool them as a metapopulation, especially if there is some marginal habitat between the main patches. If they are truly isolated such small occurrences should not be ranked higher than C.

Mapping Guidance: In agricultural regions it is easy to map useful habitat, but hard to determine what is a functional occurrence--that is viable population. With forest occurrences boundaries may be obvious. With unstable fencerow and roadside populations one can do little more than map observations.
Separation Distance for Unsuitable Habitat: 4 km
Separation Distance for Suitable Habitat: 20 km
Alternate Separation Procedure: Many of the species seem to occur mainly in unstable populations in successional or roadside areas in some parts of their range. C. PROMETHEA can be very unstable near the northern limits of its range (Tuskees et al., 1996; also personal observations of D. Schweitzer in Maine and Vermont). In many agricultural regions one can easily observe that cocoons of C. PROMETHEA are abundant some years and completely absent others in a given area often mostly in fence row, hedges, thickets and roadsides. Often one can find a few cecropia cocoons in the same thickets. In some heavily disturbed areas these unstable occurrences may be most or all of the local population. Numerous claims have been made and sometimes documented that saturniid populations move around over time, although in many cases they do not die out of areas completely but merely fluctuate. Parasitoids, native species, e.g. egg parasitoids in southern New Jersey (Schweitzer), as well as exotic COMPSILURA in New England and New York, seem to drive some fluctuations and population shifts. Regardless of cause, where large Saturniidae occur in unstable unnatural situations without apparent reservoirs in more natural forests or other habitats there is little choice but to basically record observation points. If the occurrences are along roadsides and fencerows, intervening habitats are highly unsuitable (such as farmland), and densities are such that a given patch is unoccupied most years, it may be impractical to define persistent viable occurrences. In such cases occurrences may need to be arbitrarily defined and they should not be ranked highly, or if ti is an option consider merely recording observations and not EOs.
Separation Justification: These are moths of large habitats and it makes no sense to define small occurrences separated by short distances defining habitat patches where they probably could not persist. Since fully loaded females are mostly not strong fliers it is generally believed that these moths are not good colonizers across more than a few kilometers. However it is not known how far females fly. Males are known to move tens of kilometers. Dale Schweitzer has observed numerous CALLOSAMIA PROMETHEA on their maiden flight and they are agile, powerful fliers that apparently do not lay many eggs their first night of flight. Females of some other species that are more fecund such as CITHERONIA REGALIS and HYALOPHORA CECROPIA have genuine difficulty even getting airborne and probably lay most of their eggs within a kilometer of their eclosion site. Undoubtedly once they have laid most of their eggs such females can fly far and worn females taken at lights often contain 50-200 eggs. The fact that most of the species can persist or regularly recur in small Midwestern woodlots or in small roadside thickets in vastly agricultural landscapes does imply though that partially gravid females do move between patches. These moths are mostly not habitat specialists or else occur in common forest or woodland types and almost always occur widely, though often sparsely, over large areas. These distances are meant mainly for where these species occur consistently at moderate or high densities in large habitats such as forests, desert scrub, woodlands or barrens. In extensive forests given the flight capability of these moths there is almost no chance populations within 20 km would be genetically separate and if intervening habitat were largely suitable they would in at least some years be connected. Among North American species these Specs should apply for example to most or all occurrences of ACTIAS, ANTHERAEA, CALLOSAMIA ANGULIFERA, EUPACKARDIA, EACLES, CITHERONIA among others. While C. PROMETHEA is clearly most dense in fence rows, along edges, and in thickets along moderately used automobile roads, in heavily forested regions like southern New Jersey sparsely distributed (usually <1 cocoon per hectare) forest understory populations which occur in most of the local forest types surely are most of the total population. In fact in 2001 in southern Cumberland County males were unusually numerous coming to calling females even though roadside cocoons were virtually non-existent in most areas and far lower than in the previous 12 years. A similar scenario may be true of H. CECROPIA and in some places H. COLUMBIA GLOVERI. In such cases, these Specs should be used. See alternate separation procedure for unstable occurrences without a stable reservoir.
Note then the five kilometer distance applies only across landscapes devoid of habitat or largely so, perhaps a good threshold would be >95% unsuitable such as crop land. Use the 20 kilometer distance with patchy or marginal habitat and note for many species this can include residential or urban habitat if such places provide suitable places for the cocoons..

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): 1 km
Inferred Minimum Extent Justification: Inferred is extent should really be all available habitat if the species is present at all. These moths can seldom maintain themselves in small areas and will utilize most patches to some extent in some years. One kilometer is merely a low, but practical suggested limit for use in extensive suitable habitat. A circle of this radius defines an area of about 400 hectares which does appear to approximate some of the smaller persistent occurrences for several species in southeastern Pennsylvania (Schweitzer).
Date: 20Sep2001
Author: Schweitzer, Dale F.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 06Dec2005
NatureServe Conservation Status Factors Author: Schweitzer, Dale F.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Beadle, D. and S. Leckie. Peterson field guide to moths of Northeastern North America. Houghton Mifflin Harcourt: New York, NY.

  • Covell, C.V., Jr. 1984. A field guide to the moths of eastern North America. Houghton Mifflin Co. Boston, MA. 496 pp.

  • Hall, D.W. 2014. Featured Creatures. Entomology and Nematology Department, University of Florida, Gainesville, FL. Available http://entomology.ifas.ufl.edu/creatures/bfly/regal_moth.htm. (Accessed: June 26, 2017)

  • Lotts, K., and T. Naberhaus, coordinators. 2017. Butterflies and Moths of North America. Available online: http://www.butterfliesandmoths.org/ (Version December 2018).

  • Pohl, G.R., B. Patterson and J.P.  Pelham. 2016. Annotated taxonomic checklist of the Lepidoptera of North America, North of Mexico. Working paper published online by the authors at ResearchGate.net (May 2016). 766 pp. Online:https://www.researchgate.net/publication/302570819_Annotated_taxonomic_checklist_of_the_Lepidoptera_of_North_America_North_of_Mexico

  • Sample, B.E., L. Butler, C. Zivkovich, R.C. Whitmore, and R. Reardon. 1996. Effects of Bacillus thuringiensis Berliner var. kurstaki and defoliation by the gypsy moth [Lymantria dispar (L.) (Lepidoptera: Lymantriidae)] on native Arthropods in West Virginia. Canadian Entomologist 128:573-592.

  • Schweitzer, D. F. 2017. Current versus mid 20th century statuses of moths with big summer caterpillars (Saturniidae, Sphingidae, Datana) in nothern New Jersey and eastern Pennsylvania. News of the Lepidopterists' Society 59 (3):134-141)

  • Schweitzer, D. F., M. C. Minno, and D. L. Wagner. 2011. Rare, declining, and poorly known butterflies and moths (Lepidoptera) of forests and woodlands in the eastern United States. USFS Forest Health Technology Enterprise Team, Technology Transfer Bulletin FHTET-2011-01. 517 pp.

  • Schweitzer, Dale. 1992. Memo to Kathy Schneider of December 3, 1992 concerning update of New York lepidoptera state ranks.

  • Tuskes, P. M., J. P. Tuttle, and M. M. Collins. 1996. The Wild Silk Moths of North America: A Natural History of the Saturniidae of the United States and Canada. Cornell University Press, Ithaca, New York. 250 pp.

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