Eastern Giant Swallowtail

One of the eastern giant swallowtail's most notable features is its size. Females have an average wingspan of 5.5 in (14 cm), and up to 6.9 in (18 cm), while males' average is 5.8 in (15 cm), and up to 7.4 in (19 cm). The wings are black with a horizontal yellow line across the forewings, and a diagonal yellow line across the hindwing. The underside of the wings is yellow with accents of black. A small patch of red on the ventral wing (within the small blue band) allows for distinction from the similar-looking Schaus' swallowtail. Seitz -"P. cresphontes Cr. (7a). Usually considered a slightly different variety of P. thoas. No cell-spot on the forewing; the fifth discal spot projecting further than the sixth. Claspers of the male separate above, the anal hook quite short, the lower part of the anal segment likewise quite different from that of P. thoas; harpe broad, rounded. A common species in eastern North America, occurring as far as Costa Rica in the south and southern Canada in the north; but the insect is a wanderer, which is found only now and then in the northern districts. In the United States it does not extend westward beyond the Mississippi plain, except in the Southern States. Its true home is the region adjoining the Gulf of Mexico. It occurs also on Cuba. Papilio cresphontes is a member of the Papilio thoas species group. '

The eastern giant swallowtail is common across the United States, reaching as far north as southern New England and southern Canada. South of the United States, it is found in parts of Mexico and also found in Jamaica and Cuba. The species was historically considered to occur in the western United States and into South America, but now those populations are treated as a separate species, the western giant swallowtail (Papilio rumiko), based largely on DNA evidence.

In specific local subpopulations (studied in Wisconsin, Ohio, and Florida), it was found that eastern giant swallowtail caterpillars do better on their local host plant than on other giant swallowtail host plants. The local host caused the larva to develop faster than other plants that were also edible to the larva. However, this feeding specialization hypothesis has not been tested in the species as a whole beyond these three regions.