Zebra swallowtail

Appearance

The zebra swallowtail has a wingspan of 6.4 to 10.4 cm. The triangular wings are white to greenish white with black longitudinal stripes. A pair of swordlike tails extend from the hindwings. The inner margin of the hindwing has two blue spots on the corner and a red spot near the body. A red stripe runs along the middle of the ventral hindwing. "P. marcellus" has two seasonal forms, one occurring in the spring and the other in the summer. Spring forms are smaller, more white, and have short, black tails with white tips. Summer forms are larger, have broader black stripes, and longer, black tails with white edges.

Behavior

Males will patrol near host plants in search of females, flying swiftly and directly. They usually fly 0.5 to 1.8 meters above the ground. Females will fly slowly when searching for suitable host plants. Both males and females avidly visit flowers, including species from the families Apocynaceae, Brassicaceae, Fabaceae, Lythraceae, Polemoniaceae, and Rosaceae. Males participate in a behavior known as puddling, in which individuals congregate on sand, gravel, or moist soil to obtain salts and amino acids. These nutrients aid the male in reproduction. Other food sources include rotting fruit and urine.Since the caterpillars are cannibalistic, females lay their eggs singly on pawpaw leaves or on the tree trunks. The round egg is pale green, later turning orange brown. Young caterpillars are black with lighter colored transverse stripes. Older larvae have two color forms. The more common form is green with yellow and white transverse stripes; the rarer form is black and banded with white and orange. In both forms, between the swollen thorax and the abdomen, there is a yellow, black, and bluish-white band. The larva has a yellow, foul-smelling, forked gland called an osmeterium which it will use to deter predators, especially spiders and ants. The chrysalis is either green or brown, and is more compact compared to chrysalids in the genus "Papilio". Three small horns project from the head and thorax. The chrysalis hibernates in areas of its range with cold winters.

Life cycle
File:Zebra Swallowtail laying an egg, Megan McCarty104.jpg|Female "P. marcellus" laying an egg on common pawpaw
File:Zebra Swallowtail eggs, Megan McCarty106.PNG|An egg on a host plant leaf. On the left, the egg is one day old; on the right, it is three days old.
File:Zebra Swallowtail larva, Megan McCarty121.jpg|A green form larva
File:Zebra Swallowtail larva, Megan McCarty46.jpg|A black form larva
File:Zebra Swallowtail chrysalis, Megan McCarty108.jpg|Lateral side of a chrysalis