The Baltimore has antennae that are tipped with orange. There are two orange spots near the front of the upperside of each forewing. The basic wing color is black with many white and orange marks, both on the upperside and underside of the wings. The upperside of the wings has a margin of orange spots surrounding white spots. The wingspan is one and three-fourths to two and three-fourths inches. The larva is orange with black rings, and its spines and head are black.
Turtlehead (Chelone spp.) is the host plant for the early stages of the larvae. The female lays a cluster of 100 to 700 eggs on a turtlehead plant. The eggs are red-yellow. Larvae enclose themselves in a silken nest to feed on new turtlehead leaves. The larvae overwinter in clusters wrapped in silk in leaf litter. They become active in spring and feed on other plants at that time. Pupation occurs in spring. The chrysalis is white with orange-yellow and black spots. Adults are present from June through July and feed on flower nectar.