Tiger Swallowtail Caterpillar

The Tiger swallowtail caterpillar is the larval form of one of the largest and most familiar butterflies in eastern North America, admired for its striking yellow-and-black striped wings as an adult. The caterpillar takes an entirely different approach to survival, relying on mimicry and a clever leaf shelter rather than bright warning colors.

This species is a folivore of several common hardwood trees and is often discovered by people who notice its distinctive rolled-leaf hideouts on wild cherry, tulip tree, or magnolia.

• Mature larvae are smooth, bright green, and swollen toward the front, tapering toward the rear
• Large yellow eyespots with black pupils and pale rings sit on the enlarged thorax, mimicking a snake's or lizard's eyes
• A faint blue-black band separates the thorax from the rest of the body
• Younger instars are brown and white, closely resembling a bird dropping
• No hair or spines are present on the body
• Similar to the spicebush swallowtail caterpillar, but tiger swallowtail eyespots are generally more yellow and the head shape appears more rounded

This species occurs throughout much of eastern North America, from southern Canada to the Gulf Coast, wherever suitable host trees grow. Caterpillars are found on the leaves of wild cherry, tulip tree, sweetbay magnolia, and other hardwoods in forests, woodland edges, and shaded yards from late spring through summer.

The caterpillar spends the day resting inside a shelter it makes by folding over a leaf edge with silk, emerging mainly at night to feed on foliage. Its snake-mimicking eyespots are a defense that can startle small vertebrate predators such as birds, buying the caterpillar time to escape or drop from the leaf. Like other swallowtails, it can also evert an orange osmeterium gland that releases a strong odor when disturbed. It contributes to forest food webs as prey for birds and parasitic wasps and later as a pollinator once it becomes an adult butterfly.

Eggs are laid singly on the upper surface of host leaves and hatch within about a week. The larva progresses through five instars, transforming from a bird-dropping mimic into the green, eyespotted form, folding leaves into daytime shelters as it grows. The final instar forms a mottled brown chrysalis attached by silk to a twig or bark crevice. In northern regions the species overwinters as a chrysalis with one or two generations per year, while southern populations may produce three or more broods.