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Two-tailed Swallowtail - Pterourus multicaudata
Native Species
Global Rank:
G5
State Rank:
S5
Agency Status
USFWS:
USFS:
BLM:
External Links
General Description
[From Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 5.2-6.0 cm. Very large, two tails on each hindwing. Uppersurface yellow to orangish with black border, male forewing with narrow black tiger stripes, female forewing with wider stripes on deeper yellow, hindwing with more iridescent blue in submarginal band around posterior orange spots, eyespot at anal angle may lack black pupil or pupil touches posterior margin of orange spot.
Phenology
One flight, mostly late May to June in British Columbia, May to June in California, mid-June to early August in Colorado mountains; several flights late April to early August in Colorado foothills and southward; many flights in Texas, February to November (Scott 1986). Mainly April to September (Glassberg 2001). Late may through August in Rocky Mountain states (Ferris and Brown 1981). April to early August in Colorado (Scott and Scott 1978), late March to mid-September in Oregon and Washington (Pyle 2002), late march through late August in Oregon (Warren 2005), May to August in British Columbia (Guppy and Shepard 2001).
Diagnostic Characteristics
Best determined by a combination of very large size, yellow base color with black border on each wing, narrow tiger stripes on forewing (stripes wider in female); hindwing with two tails, extensive iridescent blue in submarginal band around posterior orange spots (more extensive in females).
Species Range
Montana Range
Range Descriptions
Native
Range Comments
Southern British Columbia and southern Alberta south to central Mexico, east to western North Dakota and South Dakota, central Nebraska, central Texas (Scott 1986; Opler and Wright 1999; Glassberg 2001); to about 2134 m elevation in the Rocky Mountain states (Ferris and Brown 1981), 1481 m to 2774 m elevation (usually below 2438 m) in Colorado (Brown 1957; Scott and Scott 1978), 26 m to at least 2591 m elevation in Oregon (Warren 2005). In Montana, reported across the state from at least 32 counties (Kohler 1980; Stanford and Opler 1993; FLMNH Lepidopterists' Society database), to at least 1676 m elevation. Common in the south, rare to uncommon in the north (Glassberg 2001).
Observations in Montana Natural Heritage Program Database
Number of Observations: 141
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Migration
Non-migratory.
Habitat
Foothill slopes and canyons, moist valleys, stream sides, woodlands, parks, roadsides, suburbs, cities (Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002). Habitat in Montana not described but probably similar.
Food Habits
Larval food plants are native and exotic trees and shrubs, including members of the Rosaceae (Amelanchier, Prunus (several species), Vauquelina), Oleaceae (Fraxinus (several species), Ligustrum (multiple species)), Rutaceae (Ptelea (multiple species)), and Platanaceae (Platanus) (Scott 1986, 1992, 2006; Guppy and Shepard 2001; Graves and Shapiro 2003; Warren 2005; James and Nunnallee 2011). Adults feed on flower nectar (including Aesculus, Agastache, Alcea, Allium, Antirrhinum, Apocynum, Asclepias, Astilbe, Bouvardia, Buddleja, Campanula, Carduus, Ceanothus, Centaurea, Centranthus, Cirsium, Clematis, Crocosmia, Delosperma, Delphinium, Dianthus, Dipsacus, Echinacea, Erysimum, Eupatorium, Euphorbia, Geranium, Helianthus, Hemerocallis, Heracleum, Hesperis, Ipomoea, Ipomopsis, Iris, Jamesia, Liatris, Lobelia, Lychnis, Lythrum, Medicago, Monarda, Penstemon, Petunia, Philadelphis, Phlox, Platycodon, Prunus, Ribes, Rosa, Salvia, Saponaria, Scabiosa, Scrophularia, Silybum, Syringa, Tilia, Verbena, Viola, Zinnea), dung, and mud (Pyle 2002; Warren 2005; James and Nunnallee 2011; Scott 2014).
Reproductive Characteristics
Females lay eggs singly on uppersurface of host plant leaves (Scott 1986, 1992, 2006; James and Nunnallee 2011), producing about 55 eggs during 10 days of egg-laying (Guppy and Shepard 2001). Eggs hatch within 7-10 days, develop from L1 instar to L5 instar and pupae in about 33-42 days. Larvae eat host plant leaves, rest on silk mat on upper leaf surface when not feeding, overwinter (diapause) as pupae on base of trunk or on stems (Scott 1979, 1986; Guppy and Shepard 2001; James and Nunnallee 2011). Males patrol throughout the day along canyon bottoms, forest openings, roads, lake margins, stream banks, foliage barriers, through urban landscapes in search of females (Scott 1975b, 1986; Guppy and Shepard 2001; Warren 2005; James and Nunnallee 2011).
Stewardship Responsibility
References
- Literature Cited AboveLegend:
View Online Publication
Brown, F.M. 1957. Colorado Butterflies. Proceedings; Numbers Three through Seven. Denver Museum of Natural History, Denver, Co.- Ferris, C.D. and F.M. Brown (eds). 1981. Butterflies of the Rocky Mountains. Univ. of Oklahoma Press. Norman. 442 pp.
- Glassberg, J. 2001. Butterflies through Binoculars: A Field Guide to the Butterflies of Western North America. Oxford University Press.
- Graves, S.D. and A.M. Shapiro. 2003.Exotics as host plants of the California butterfly fauna. Biological Conservation 110: 413-433.
- Guppy, C.S. and J.H. Shepard. 2001. Butterflies of British Columbia: including western Alberta, southern Yukon, the Alaska Panhandle, Washington, northern Oregon, northern Idaho, northwestern Montana. UBC Press (Vancouver, BC) and Royal British Columbia Museum (Victoria, BC). 414 pp.
- James, D.G. and D. Nunnallee. 2011. Life histories of Cascadia butterflies. Corvallis, OR: Oregon State University Press. 447 p.
- Kohler, S. 1980. Checklist of Montana Butterflies (Rhopalocera). Journal of the Lepidopterists' Society 34(1): 1-19.
- Opler, P.A. and A.B. Wright. 1999. A field guide to western butterflies. Second edition. Peterson Field Guides. Houghton Mifflin Company, Boston, Massachusetts. 540 pp.
- Pyle, R.M. 2002. The butterflies of Cascadia: a field guide to all the species of Washington, Oregon, and surrounding territories. Seattle Audubon Society, Seattle, Washington. 420 pp.
- Scott, J.A. 1975b. Mate-locating behavior of western North American butterflies. Journal of Research on the Lepidoptera 14:1-40.
- Scott, J.A. 1979. Hibernal diapause of North American Papilionoidea and Hesperioidea. Journal of Research on the Lepidoptera 18(3): 171-200.
- Scott, J.A. 1986. The butterflies of North America: a natural history and field guide. Stanford University Press, Stanford, California.
- Scott, J.A. 1992. Hostplant records for butterflies and skippers (mostly from Colorado) 1959-1992, with new life histories and notes on oviposition, immatures, and ecology. Papilio new series #6. 185 p.
- Scott, J.A. 2006. Butterfly hostplant records, 1992-2005, with a treatise on the evolution of Erynnis, and a note on new terminology for mate-locating behavior. Papilio new series #14. 74 p.
- Scott, J.A. 2014. Lepidoptera of North America 13. Flower visitation by Colorado butterflies (40,615 records) with a review of the literature on pollination of Colorado plants and butterfly attraction (Lepidoptera: Hersperioidea and Papilionoidea). Contributions of the C.P. Gillette Museum of Arthopod Diversity. Fort Collins, CO: Colorado State University. 190 p.
- Scott, J.A. and G.R. Scott. 1978. Ecology and distribution of the butterflies of southern central Colorado. Journal of Research on the Lepidoptera 17(2): 73-128.
- Stanford, R.E. and P.A. Opler. 1993. Atlas of western USA butterflies: including adjacent parts of Canada and Mexico. Unpubl. Report. Denver and Fort Collins, Colorado 275 pp.
- Warren, A.D. 2005. Lepidoptera of North America 6: Butterflies of Oregon, their taxonomy, distribution, and biology. Contributions of the C. P. Gillette Museum of Arthropod Diversity, Colorado State University. Fort Collins, Colorado. 406 pp.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- Allen, T.J., J.P. Brock, and J. Glassberg. 2005. Caterpillars in the field and garden: a field guide to the butterfly caterpillars of North America. Oxford University Press.
- Brock, J.P. and K. Kaufman. 2003. Kaufman Field Guide to Butterflies of North America. Houghton Mifflin Company, New York, NY 284 pp.
- Forister, M.L., C.A. Halsch, C.C. Nice, J.A. Fordyce, T.E. Dilts, J.C. Oliver, K.L. Prudic, A.M. Shapiro, J.K. Wilson, J. Glassberg. 2021. Fewer butterflies seen by community scientists across the warming and drying landscapes of the American West. Science 371:1042-1045.
- Forister, M.L., E.M. Grames, C.A. Halsch, K.J. Burls, C.F. Carroll, K.L. Bell, J.P. Jahner, et al. 2023. Assessing risk for butterflies in the context of climate change, demographic uncertainty, and heterogeneous data sources. Ecological Monographs 93(3):e1584. https://doi.org/10.1002/ecm.1584
- Layberry, R.A., P.W. Hall, and J.D. LaFontaine. 1998. The Butterflies of Canada. University of Toronto Press. 280 pp. + color plates.
- Maxell, B.A. 2016. Northern Goshawk surveys on the Beartooth, Ashland, and Sioux Districts of the Custer-Gallatin National Forest: 2012-2014. Montana Natural Heritage Program. Helena, MT. 114pp.
- Opler, P.A., K. Lotts, and T. Naberhaus, coordinators. 2010. Butterflies and moths of North America. Big Sky Institute, Bozeman, MT. Available at: www.butterfliesandmoths.org (Accessed 15 June 2015).
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