Eastern Tiger Swallowtail
(Papilio glaucus)
Quick ID
Type: Butterfly (Lepidoptera)
Wingspan: 3-5.5 inches
Color: Bright yellow with black tiger stripes; males have more vivid markings
Tail: Distinct "swallowtail" extensions on hindwings
Sexual Dimorphism: Females may be yellow or dark (black morph)
Ecological Role
Pollinator: Visits a variety of flowers including lilac, milkweed, and tulip tree.
Host Plant: Larvae feed on leaves of tulip tree, wild cherry, and ash.
Food Web: Caterpillars serve as prey for birds and predatory insects.
At-a-Glance
đ Wingspan: 3â5.5 in
âď¸ Sun: Full sun preferred (gardens/flowering plants)
đż Host Plants: Tulip tree, wild cherry, ash
đ Pollinator Value: High â nectar source for flowers
â ď¸ Human safety: Safe; caterpillars may secrete mild irritants
Where to Find It
Range: Eastern North America, from New England to Florida, west to the Great Plains.
Habitats: Forest edges, gardens, parks, riversides.
Active Seasons: Adults spring through late summer; caterpillars in early summer.
Look-Alikes
Spicebush Swallowtail (Papilio troilus) â smaller, lacks yellow tiger stripes, has blue markings on hindwings.
Black Swallowtail (Papilio polyxenes) â black wings with yellow spots; no tiger stripes.
Why It Matters
Eastern Tiger Swallowtails are keystone pollinators in many eastern U.S. gardens and forests. Observing them can indicate a healthy local ecosystem.
Safety
Safe to handle lightly as adults; caterpillars may exude mild irritants if disturbed.
Avoid picking plants with caterpillars unless observing only.
Fun Fact
The Eastern Tiger Swallowtail caterpillar has a very cool defense feature on its head:
It carries an osmeterium â a bright orange, forked, fleshy organ tucked just behind the head. When the caterpillar feels threatened, it everts (pops out) the osmeterium, releasing a strong, unpleasant smell that deters predators like ants, spiders, and birds.
From the front, the caterpillar also has false âeye spotsâ on its thorax (just behind the actual tiny head). These spots make it look like a little snake, further confusing would-be predators.
So in short:
False eyespots = visual defense (scare predators).
Osmeterium = chemical defense (stinky deterrent).
Also, adults are fast fliers and can travel miles to find nectar.
Dig Deeper
Curious for more? Read the blog.
Recommended Book References
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