Specific epithet philenor (Greek φιληνωρ) literally means "fond of a man/men" or "loving one's husband". Linnaeus doesn't explain what this has to do with butterflies.
Numbers
Butterflies of America lists 5 subspecies, of which 2 are native to our area:
philenor (Linnaeus, 1771)
hirsuta (Skinner, 1908)
For more details on the subspecies of the Pipevine Swallowtail, refer to the following:
Iridescent blue/black pattern on upper surface is distinctive when fresh. Can be confused with other members of its mimicry complex--see comments below. The Pipevine flutters its wings incessantly while nectaring--I suspect this is part of its mechanisms for advertising distastefulness. (This is original speculation by the author--PC.) Some others in its complex, notably the Black Swallowtail, seem to do this too.
Male has very iridescent upper surfaces of hindwings. Female has less striking iridescence. Underside has a single median row of orange spots which do not touch each other.
Male: Female: Underside:
Caterpillar is quite distinctive, may be a mimic of the tropical onychophorans, called velvet worms. Dark brownish black (occasionally smoky red) with soft fleshy tentacle-like projections, usually red-orange dorsal warts over abdomen. Tentacles on T1 twice as long as those on following segments.
Chrysalis brown or green, similar to Battus polydamas - see David Ferguson's comments on this image for a description of the differences:
In eastern US, old fields, etc. near woodlands with hostplant.
Season
Mid-summer in eastern United States. Does not fly as late into fall as other swallowtails. Caterpillars present from June into fall in temperate areas.
Food
Larvae feed on Aristolochia species. These include "Pipevine" or "Dutchman's Pipe", Aristolochia species (tomentosa, durior, reticulata, californica), as well as Virginia Snakeroot, Aristolochia serpentaria.
Larvae presumably take up toxic secondary compounds (including Aristolochic acid) from their hostplant. Both larvae and adults are believed toxic to vertebrate predators, and both have aposematic (warning) coloration.
Adults nectar on a variety of flowers, including asteraceae. Males take fluids from damp sand.
Life Cycle
Two or three flights per year in North Carolina. Flies all year in tropical Mexico. Overwinters as chrysalis in temperate areas. In North Carolina, P. Coin has noticed two colors of chrysalises produced in mid-summer. One was green, and an adult emerged from these in about two weeks. Several others were dark brown. One overwintered, (chrysalis formed May 30, 2004) emerging on May 10, 2005, almost one year later.
There is some indication that the Spicebush and Black Swallowtails are also distasteful, so the complex is partly Mullerian as well (1). In the central and western US, Old World Swallowtail (Papilio machaon, form bairdi), Indra Swallowtail (Papilio indra), and Ozark Swallowtail (Papilio joanae) have dark blue/black forms, probably mimics of the Pipevine Swallowtail (2).
This butterly can discriminate between two Aristolochia host species visually by leaf shape.(3)
See Also
Mimics: Eastern Tiger Swallowtail (female, dark phase), Black Swallowtail (female), Spicebush Swallowtail, Red-spotted Purple, Diana Fritillary. See Black Swallowtail for comparisons of the mimics.
Larva of Battus polydamas is somewhat similar, but fleshy projections are orange, shorter on T1 and longer on the rest of the body than those of B. philenor. Usually has muted diagonal striping.
