Guide

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Mourning cloaks: butterflies that winter as adults

April and October

Mourning cloak butterflies survive winter as full-grown adults, tucked inside hollow trees or woodpiles, and count among the earliest butterflies to fly each spring, sometimes before the snow has fully melted. In fall the adults feed until they tuck away for winter, and one has been seen flying in Massachusetts in every month of the year.

Why this time of year

In April the adults that spent the winter tucked away are among the first butterflies flying, and in October adults are out feeding before they hide for the winter.

How to notice it

  1. Go out on a mild day, especially after several warm days in a row.
  2. Check oak trunks with oozing sap, rows of sapsucker holes, and fallen rotting fruit, where it often feeds.
  3. Look for deep maroon wings with a ragged pale-yellow border.
  4. If nothing is flying, check the same spots for one resting with wings closed, showing an ash-gray underside with a pale border.

Try this with kids: This butterfly spends the winter as a grown-up butterfly, hidden in a hollow tree or woodpile. Can you find one out on a warm day?

overwinters as an adult: spends winter as a full-grown butterfly instead of an egg, caterpillar, or chrysalis

Sources

  • massaudubon.orgMass Audubon Massachusetts Butterfly Atlas: overwinters as an adult; normal flight period April through October; seen in flight in Massachusetts in every month; among the earlier species in spring, even flying before the snow has fully melted.
  • umass.eduUMass Extension: the adult is the overwintering stage, making it one of the first butterflies seen in spring.
  • massbutterflies.orgMassachusetts Butterfly Club: flight period mainly late March to late October; overwinters as an adult; the only Massachusetts butterfly recorded flying in every month.

Checked against these sources on September 28, 2026.

In the guide for April, October

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