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Montana Field Guides

Old World Swallowtail - Papilio machaon

Global Rank: G5
State Rank: S4

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General Description
Not all authorities agree on the specific status of members in the Papilio machaon group (see Scott 1986; McCorkle and Hammond 1988; Sperling and Harrison 1994; Guppy and Shepard 2001; Pyle 2002; Warren 2005), with some treating P. m. bairdii and P. m. oregonius as full species instead of subspecies. Given the taxonomic uncertainty and instability, this account probably includes information pertaining to more than one taxon, possibly more than one species.

[From Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 4.0-4.5 cm. Variable in color, with black or yellow forms, tailed. Tegulae (thorax at wing base) yellow, abdomen mostly yellow in yellow forms, abdomen black with two or three rows of yellow spots along sides in black forms. Uppersurface usually with broad yellow median bands (narrower in black forms), blue postmedian hindwing spots, orange eyespot at anal angle of hindwing with pupil not centered (off-center and touching inner margin or oblong black patch at lower margin). Undersurface with yellow bands tinges with orange.

One flight, mostly June to early July in the north (Alaska, northern British Columbia), two or three flights farther south, May to September (Scott 1986). Mainly May to June, mid-July to September (Glassberg 2001). May to August in Rocky Mountain states (Ferris and Brown 1981), early May to late August in Colorado (Scott and Scott 1978), mid-March to mid-October in Oregon and Washington (Pyle 2002), two or three flights mid-March through September in Oregon (Warren 2005), one flight June and July in British Columbia (Guppy and Shepard 2001).

Diagnostic Characteristics
Best determined by a combination of single long tail, thorax shoulders usually yellow or gold, abdomen mostly yellow with black stripe in yellow forms, abdomen black with two or three rows of yellow spots along sides in black forms, orange eyespot at anal angle of hindwing with pupil not centered (off-center and touching inner margin or oblong black patch at lower margin).

Species Range
Montana Range

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Range Comments
Holarctic. In North America, Alaska south through Canada and western US to Arizona, southern California, southern New Mexico, east in Canada to western Quebec, in US to western Dakotas, western Nebraska, northwestern Kansas (Scott 1986; Opler and Wright 1999; Glassberg 2001); usually below 2438 m elevation in Rocky Mountain states (Ferris and Brown 1981), 1402 m to 2926 m elevation (rare above 2438 m) in central Colorado (Scott and Scott 1978), 26 m to at least 1951 m elevation in Oregon (Warren 2005). In Montana, reported across the state on both sides of continental divide from at least 32 counties (Kohler 1980; Stanford and Opler 1993; FLMNH Lepidopterists' Society database), to at least 1829 m elevation. Rare to uncommon (Glassberg 2001).

Summary of Observations Submitted for Montana
Number of Observations: 1

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Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Non-migratory, although somewhat migratory in Europe. Males can fly several km to reach hilltops and ridgetops for courtship (Scott 1986).

Open woodland, aspen, sagebrush steppe, prairie, tundra, arid canyons, river valleys, arid hills (Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002). Habitat in Montana not described but probably similar. In Greater Yellowstone Ecosystem, reported from semi-arid mountains (Debinski and Pritchard 2002).

Food Habits
Larval food plants primarily Artemisia (multiple species, but A. dracunculus in our region), also Heracleum, Petasites, and Zizia. In lab, feed on members of the Apiaceae Daucus, Foeniculum, and Pastinaca (Emmel and Emmel 1963; Newcomer 1964; Ferris and Brown 1981; Scott 1986, 1992; Warren 2005; James and Nunnallee 2011). Adults feed on flower nectar (including Asclepias, Balsamorhiza, Carduus, Castilleja, Cirsium, Cleome, Liatris, Medicago, Petunia, Phlox, Rosa, Rudbeckia, Verbena, Zinnea) and mud (Newcomer 1964; Pyle 2002; Scott 2014).

Reproductive Characteristics
Females lay eggs singly on host plant (Scott 1986, 1992; James and Nunnallee 2011). Eggs hatch in about 6-7 days (depending on temperature), develop from L1 instar to L5 instar and pupae in about 21-35 days (depending on Temperature), adults eclosing (emerge) from pupae in same year about 10-15 days, otherwise overwinter at least 9 months (possibly more than one winter) as pupae (Newcomer 1964; Scott 1979; James and Nunnallee 2011). Larvae feed on host plant leaves, rest on stems or among leaves, build no nests, wander for a day or two as L5 instar before pupating on host plant stem (Newcomer 1964; Scott 1986; James and Nunnallee 2011). Males patrol and perch throughout the day, often on hilltops and ridge crests, searching for passing females (Scott 1975b, 1986; Guppy and Shepard 2001; James and Nunnallee 2011).

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Old World Swallowtail — Papilio machaon.  Montana Field Guide.  .  Retrieved on , from