Invertebrates
Spicebush Swallowtail
Papilio troilus · also called spicebush swallowtails
A bird investigating a curled leaf on a spicebush shrub hesitates at the sight of two large, staring eyespots peering back, entirely unaware that the “creature” watching it is nothing more than a harmless caterpillar putting on a remarkably convincing act.
Overview
The spicebush swallowtail, Papilio troilus, is a dark-winged butterfly native to forest and woodland edge habitat across a broad range of eastern North America. Its caterpillar’s convincing snake-mimicking eyespots and self-made leaf shelter make it one of the more elaborately defended and behaviourally interesting butterflies in eastern woodlands.
A caterpillar hiding behind a costume and a curtain
Between its folded-leaf daytime hideout and its snake-like false eyes, a spicebush swallowtail caterpillar relies on two separate layers of defence, staying out of sight when possible and bluffing convincingly when it isn’t.
Status
Least Concern — widespread and common across suitable forest habitat throughout eastern North America.
Spicebush Swallowtail: common questions
Why does the spicebush swallowtail caterpillar have fake eyes?
A spicebush swallowtail caterpillar develops two large, false eyespots on its swollen thorax, a snake-like appearance intended to startle and deter potential predators such as birds, which may mistake the harmless caterpillar for a small, more threatening snake at a quick glance.
Why does the spicebush swallowtail caterpillar fold a leaf around itself?
A spicebush swallowtail caterpillar folds a leaf over itself using silk to create a protective daytime shelter, hiding inside to avoid predators during daylight hours and emerging mainly at night to feed on its host plant more safely.
How did the spicebush swallowtail get its name?
The spicebush swallowtail takes its common name directly from spicebush, one of its two primary caterpillar host plants alongside sassafras, both of which the caterpillars rely on for food throughout their development.
Where does the spicebush swallowtail live?
The spicebush swallowtail is native to forest and woodland edge habitat across a broad range of eastern North America, generally found wherever spicebush or sassafras host plants are available.