The wingspread of males is 3.0 to 4.6 cm and females 2.9 to 4.9. The upper surface of the wings is white with black stripes. The hind wings have very long tails. The zebra swallowtail exhibits seasonal dimorphism. Early spring specimens are lighter in color, smaller, and have tails only about half as long as summer forms.
Eggs are pale green.
Young larvae are dark colored with many transverse black, yellow, and white bands. Older larvae are green with broad blue, black, and yellow transverse bands between the thorax and abdomen and usually yellow bands between abdominal segments and numerous fine transverse black lines on thorax and abdomen. However, larvae exhibit color polymorphism. The osmeterium is yellow. Pupae are green or brown with light lines simulating a leaf-like texture and are supported with a silken girdle.