Monarchs get all the headlines, sure, but mourning cloak butterflies are first on the scene in spring. They bravely emerge from their winter hibernation hiding spots—under tree bark or in rock crevices—when snow is still on the ground. They’re one of our few butterfly species hardy enough to survive the cold as adults.
On sunny, thawing days in March, you’ll find these butterflies basking on rocks and trees, warming themselves in preparation for flight. They shiver their fuzzy wings to raise their body temperature—up to 25°C higher than the air temperature—before lift-off. If they’re too cold, they can’t fly.
By June, mourning cloak caterpillars have hatched, from yellow-brown eggs clustered in a ring around twigs and slim branches. They’re also called spiny elm caterpillars—for good reason: they’re black and spiny, with orange-red spots, and they feed in part on elm leaves.
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