Euphydryas phaeton - (Drury, 1773)
Baltimore Checkerspot
Taxonomic Status: Accepted
Related ITIS Name(s): Euphydryas phaeton (Drury, 1773) (TSN 778057)
French Common Names: baltimore
Unique Identifier: ELEMENT_GLOBAL.2.107962
Element Code: IILEPK4060
Informal Taxonomy: Animals, Invertebrates - Insects - Butterflies and Moths - Butterflies and Skippers
Kingdom Phylum Class Order Family Genus
Animalia Mandibulata Insecta Lepidoptera Nymphalidae Euphydryas
Genus Size: C - Small genus (6-20 species)
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Concept Reference
Concept Reference: Opler, P. A., and A. D. Warren. 2002. Butterflies of North America. 2. Scientific Names List for Butterfly Species of North America, north of Mexico. C.P. Gillette Museum of Arthropod Diversity, Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, Colorado. 79 pp.
Concept Reference Code: B02OPL01EHUS
Name Used in Concept Reference: Euphydryas phaeton
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 12Feb2017
Global Status Last Changed: 12Feb2017
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Declining in many places, imperiled in some southern parts of the range, however, for now not of range-wide concern. Increased use of exotic Plantago lanceolata as a foodplant starting in Connecticut in the 1970s could be an important adaptation. On the other hand threats from deer are probably increasing. Should be monitored.
Nation: United States
National Status: N4 (30Sep1998)
Nation: Canada
National Status: N5 (12Feb2017)

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 Alabama (SU), Arkansas (S4), Connecticut (S4), Delaware (S1), District of Columbia (SH), Georgia (SU), Illinois (S3), Indiana (S2), Iowa (S2), Kansas (S1S2), Kentucky (S2S3), Maine (S4), Maryland (S2), Massachusetts (S4), Michigan (S4), Minnesota (S4), Mississippi (SNR), Missouri (S4), New Hampshire (S4), New Jersey (S4), New York (S4), North Carolina (S2), Ohio (SU), Oklahoma (S4?), Pennsylvania (S3), Rhode Island (S4), South Carolina (SNR), Tennessee (S4), Vermont (S4), Virginia (SU), West Virginia (S2), Wisconsin (S4)
Canada Manitoba (S2), New Brunswick (S4), Nova Scotia (S2S3), Ontario (S4), Prince Edward Island (S4), Quebec (S4S5)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent: >2,500,000 square km (greater than 1,000,000 square miles)
Range Extent Comments: SE Manitoba to Nova Scotia, and south to Nebraska, Arkansas, and in the mountains to Georgia.

Number of Occurrences: 81 to >300

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

Number of Occurrences with Good Viability/Integrity: Unknown

Overall Threat Impact: High
Overall Threat Impact Comments: Development, e.g. filling marshes, has probably destoyed most habitats. However now deer may be the largest threat. This has been best documented in Maryland, but probably is or will become a threat in most places where Chelone glabra or Aureolaria spp. are the main foodplants.

Short-term Trend: Decline of 10-30%

Long-term Trend: Unknown

Intrinsic Vulnerability: Not intrinsically vulnerable

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.

Other NatureServe Conservation Status Information

Protection Needs: in many parts of the range deer control will be, or already is, essential. In most places metapopulations are probably necessary to perpetuate this species. Even in southern Connecticut in the 1970s and early 1980s when this was basically are fairly common butterfly and deer were not a problem, colonies often died out, but recolonization was also frequent and wandering females could turn up even in cities. D. Schweitzer

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) SE Manitoba to Nova Scotia, and south to Nebraska, Arkansas, and in the mountains to Georgia.

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.
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AL, AR, CT, DC, DE, GA, IA, IL, IN, KS, KY, MA, MD, ME, MI, MN, MO, MS, NC, NH, NJ, NY, OH, OK, PA, RI, SC, TN, VA, VT, WI, WV
Canada MB, NB, NS, ON, PE, QC

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
DE New Castle (10003)
IA Allamakee (19005), Butler (19023), Cerro Gordo (19033), Chickasaw (19037), Floyd (19067), Henry (19087), Lee (19111), Linn (19113), Louisa (19115), Mitchell (19131), Muscatine (19139), Winneshiek (19191), Worth (19195)
IN Brown (18013)*, Kosciusko (18085)*, La Porte (18091), Lagrange (18087), Lake (18089), Morgan (18109), Noble (18113)*, Porter (18127), Steuben (18151), Tippecanoe (18157), Wabash (18169), Wayne (18177), Whitley (18183)*
MD Carroll (24013), Prince Georges (24033)
NC Alleghany (37005), Ashe (37009), Avery (37011), Buncombe (37021), Graham (37075), Haywood (37087), Henderson (37089), Jackson (37099), Macon (37113), Madison (37115), Mitchell (37121), Transylvania (37175)*, Watauga (37189)
OK Ottawa (40115)
PA Adams (42001), Berks (42011), Butler (42019), Carbon (42025), Columbia (42037), Crawford (42039), Juniata (42067), Lancaster (42071), Lebanon (42075), Lehigh (42077), Luzerne (42079), Lycoming (42081), Mifflin (42087), Monroe (42089), Perry (42099), Potter (42105), Schuylkill (42107), Sullivan (42113), Tioga (42117), Venango (42121), Warren (42123), York (42133)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
02 Middle Delaware-Mongaup-Brodhead (02040104)+, Lehigh (02040106)+, Schuylkill (02040203)+, Brandywine-Christina (02040205)+, Upper Susquehanna-Lackawanna (02050107)+, Sinnemahoning (02050202)+, Pine (02050205)+, Lower West Branch Susquehanna (02050206)+, Lower Susquehanna-Penns (02050301)+, Lower Juniata (02050304)+, Lower Susquehanna-Swatara (02050305)+, Lower Susquehanna (02050306)+, Gunpowder-Patapsco (02060003)+, Patuxent (02060006)+, Monocacy (02070009)+
03 Upper Broad (03050105)+, Saluda (03050109)+*
04 Little Calumet-Galien (04040001)+, St. Joseph (04050001)+
05 Upper Allegheny (05010001)+, Conewango (05010002)+, Middle Allegheny-Tionesta (05010003)+, Connoquenessing (05030105)+, Upper New (05050001)+, Whitewater (05080003)+, Eel (05120104)+, Middle Wabash-Deer (05120105)+, Tippecanoe (05120106)+*, Upper White (05120201)+, Lower East Fork White (05120208)+*
06 Upper French Broad (06010105)+, Pigeon (06010106)+, Nolichucky (06010108)+, Upper Little Tennessee (06010202)+, Tuckasegee (06010203)+, Lower Little Tennessee (06010204)+
07 Upper Iowa (07060002)+, Upper Wapsipinicon (07080102)+, Flint-Henderson (07080104)+*, Skunk (07080107)+, Upper Cedar (07080201)+, Shell Rock (07080202)+, Winnebago (07080203)+, West Fork Cedar (07080204)+, Lower Cedar (07080206)+, Lower Iowa (07080209)+, Lower Des Moines (07100009)+, Kankakee (07120001)+
11 Lake O' the Cherokees (11070206)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Basic Description: Butterfly, Nymphalidae.
Habitat Type: Terrestrial
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Palustrine Habitat(s): Bog/fen, HERBACEOUS WETLAND, Riparian, SCRUB-SHRUB WETLAND
Terrestrial Habitat(s): Grassland/herbaceous, Old field, Woodland - Hardwood
Habitat Comments: In most cases wetlands or at least moist meadows with a lot of CHELONE GLABRA. However starting by the 1980s there are populations in southern New England using PLANTAGO as the foodplant for all instars and these occur in artificial habitats. Subspecies OZARKAE is usually in dry rocky oak woodlands with larger AUREOLARIA (formerly GERARDIA) as the foodplants. Such habitats and this genus are occasionally used in the Boston area (Schweitzer), in New York (Shapiro, 1974) and Connecticut. The well known AUREOLARIA feeding occurrence on West Rock near New Haven is ephemeral and absent most years (Schweitzer many observations 1975-1984)-- with several obvious wetland sources of colonists.
Adult Food Habits: Nectarivore
Food Comments: Beside the normal foodplants, post hibernation larvae will eat a number of others--mostly genera with iridoid glycosides including several herbs and even small ash trees. Caterpillar Hosts: Plants where eggs are laid and that caterpillars eat before hibernating are turtlehead (Chelone glabra), hairy beardtongue (Penstemon hirsutus), English plantain (Plantago lanceolata), and false foxglove (Aureolaria). After overwintering, caterpillars may continue to use these plants, but may also wander and feed on unrelated plants including arrowwood (Viburnum recognitum), common lousewort (Pedicularis canadensis), Japanese honeysuckle (Lonicera japonica), and white ash (Fraxinus americana). Adult Food: Nectar from flowers of milkweed, viburnum, and wild rose (Lotts and Naberhaus 2017).
Phenology Comments: Always one brood with mid instar larvae hibernating.
Economic Attributes Not yet assessed
Management Summary Not yet assessed
Population/Occurrence Delineation
Group Name: Small or Localized Nymphalids

Use Class: Not applicable
Minimum Criteria for an Occurrence: A location where a population occurs, or has occurred, where there is potential for persistence or continued recurrence. Minimally a place where the species has been verified where there is adequate larval foodplant, nectar and overall habitat to sustain a population. Repeated occurrences of adults out of habitat on flowers, e.g. in gardens are not occurrences. Verification standards vary with species. For all a collected specimen is preferable except with taxa for which this would be illegal. Good photographs will always, almost always, or sometimes suffice depending on species and locality. Photographs are much more likely to suffice if both the upper and underside are clearly shown.
Mapping Guidance: In general larval foodplants, but sometimes also nectar plants, are the main basis for EOs. These plus general habitat features can be used as boundaries. With metapopulations the separate demes often should be mapped. Consult habitat and foodplant comments fields for species-specific information on what constitutes suitable habitat when mapping occurrences for individual species.
Separation Barriers: Minimal data and probably vary with species. Usually not relevant.
Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 10 km
Alternate Separation Procedure: Multiple colonies within an overall community matrix such as openings within pine barrens or savannas, or foodplant patches within a wetland complex, prairie remnant, canyon or along a stream should generally be treated as one metapopulation occurrence by using the suitable habitat distance, especially if the foodplant occurs to some degree between the colonies.
Separation Justification: There are few good data for most species, but some of the California Euphydryas taxa have been intensively studied by Paul Ehrlich and others as have some comparable European species. These data and many casual observations all suggest metapopulation structures are common and that females sometimes leave colonies and disperse for kilometers even into and through urban areas and even rarely between low peaks. An extreme example might be Euphydryas phaeton around New Haven Connecticut at least into the 1980s (before Plantago was adopted as a primary foodplant). Valley marsh Chelone feeding populations would sporadically colonize ridgetops and produce colonies on Aureolaria. These colonies usually did not persist more than a year or two but periodically reappeared. At the same time wetland colonies sometimes were wiped out when population explosions caused larval starvation, but such places got recolonized within a few years (observations of D. Schweitzer and others). Chlossyne harrisii also is subject to frequent extirpation and recolonization at least southward. Gatrelle and others report that even the highly restricted Phyciodes batesii maconensis moves along forest roads. Within most of its range P. tharos will reliably find virtually every patch of suitable asters, even colonizing single large plants left in lawns.
It appears then that populations within a few kilometers will usually be somewhat connected. As with most Lepidoptera, contiguous suitable habitat is rarely only partially occupied. If the species occurs at all, all such habitat should be assumed occupied at least some of the time. However, for practical considerations observations more than 10 kilometers apart should be considered separate pending more information. Both distances are arbitrary but seem consistent with what is known.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): 2 km
Inferred Minimum Extent Justification: In the overwhelming majority of situations with most taxa likely to be tracked and mapped the inferred extent is simply the entire contiguous or nearly contiguous suitable habitat, which will usually be a few hundred hectares or less or a fairly obvious collection of patches within a well defined community. However in situations with extensive contiguous habitat or closely proximate patches (e.g. along a ridgetop or along a river) it is unreasonable to assume it is consistently unoccupied, but occupancy should not be inferred over more than 2 kilometers without additional data.
Date: 12Sep2001
Author: Schweitzer, Dale F.
Notes: These Specs are not appropriate for migratory species.
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 14Aug2009
NatureServe Conservation Status Factors Author: Schweitzer, D.F.
Element Ecology & Life History Edition Date: 18May2001
Element Ecology & Life History Author(s): SCHWEITZER, D.F.

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

  • Allen, T.J. 1997. The butterflies of West Virginia and their caterpillars. Pittsburgh, PA. University of Pittsburgh Press.

  • Belth, Jeffrey E. 2013. Butterflies of Indiana A Field Guide. Indiana University Press.Bloomington, IN.

  • Bess, James. 2005. A Report on the Remnant-Dependent Insects of the Coastal Zone Natural Area Remnants in Northwest Indiana. 23 pp..

  • Bowers, M. Deane. 1978. Overwintering Behavior in Euphydryas Phaeton (Nymphalidae). Journal of the Lepidopterists' Society. 32(4). pp. 282-288. : 282-288.


  • General Status 2015, Environment Canada. 2015. Manitoba butterfly species list and subnational ranks proposed by Environment Canada contractor.

  • Huber, R. L. 1981. An updated checklist of Minnesota butterflies. Minnesota Entomological Association Newsletter 14(3):15-25.

  • Klassen,P.,Westwood, A.R., Preston. W.B. and W.B. McKillop. 1989. The butterflies of Manitoba. Manitoba Museum of Man and Nature. Winnipeg. 290 pp.

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

  • Natural Resources Commission. 2014. Roster of Indiana Animals, Insects, and Plants That Are Extirpated, Endangered, Threatened or Rare. Information Bulletin #2 (Sixth Amendment. 20pp.

  • Opler, P. A., and A. D. Warren. 2002. Butterflies of North America. 2. Scientific Names List for Butterfly Species of North America, north of Mexico. C.P. Gillette Museum of Arthropod Diversity, Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, Colorado. 79 pp.

  • Pelham, J. P. 2008. A catalogue of the butterflies of the United States and Canada with a complete bibliography of the descriptive and systematic literature. The Journal of Research on the Lepidoptera. Volume 40. 658 pp. Revised 14 February, 2012.

  • 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 (May 2016). 766 pp. Online:

  • Pohl, G.R.  J-F. Landry, B.C. Schmidt, J.D. Lafontaine, J.T. Troubridge, A.D. Macaulay, E.van Nieukerken, J.R. deWaard, J.J. Dombroskie, J. Klymko, V. Nazari and K. Stead. 2018. Annotated checklist of the moths and butterflies (Lepidoptera) of Canada and Alaska. Pensoft Publishers. 580 pp.

  • Shuey, John. 1995. Indiana S-Ranks for Butterflies. Memorandum to Cloyce Hedge. 10 pp.

  • Shull, E. M. 1987. Butterfly Information. Letter to Michelle Martin. 2 pp.

  • Shull, Ernest M. 1987. The Butterflies of Indiana. Publ. by Indiana Acad. Science, distributed by Indiana Univ. Press, Bloomington/Indianapolis, 262 pp.

  • Shull, Ernest. 1977. Colony of Pieris napi oleracea (Pieridae) in Indiana. 31(1) J. Lepid. Soc. 68-70.

  • Young, Frank N. 1956. Euphydryas Phaeton in Southern Indiana. Lep. News Field Notes. 10(1-2): 46.

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