How Butterflies Survive the Cold Maine Winters

Migration 

Maine winters are harsh, so many species escape the cold by migrating to warmer weather.

Two-Way Migration:

These butterflies leave Maine in the fall to find warmer climates, and the same individuals will then return to Maine in the spring. They often travel to Texas or Georgia, but some will overwinter in Virginia. Some populations of red admirals, American ladies, and buckeyes make these kinds of there-and-back flights.

One-Way Migration: 

Some species of butterflies need multiple generations to migrate to warmer areas, which you can think of as a long-distance relay race. An individual travels a distance, will lay eggs, and after hatching and pupating, their offspring will continue the next leg of the migration journey. It can often take 5-7 generations to make this trip. Some of these species that make these lengthy trips are monarchs (who overwinter in Mexico) and question marks and Eastern commas (who both overwinter in the Gulf Coast).

Overwintering

Some species of butterflies and moths stick around Maine and can survive the cold by overwintering in their pupa or pre-pupal stages. Some of these species are black swallowtails, pipevine swallowtails, spicebush swallowtails, giant swallowtails, cecropia moth, luna moth, and Polyphemus moth. 

The mourning cloak butterfly is the only species in Maine that can overwinter as an adult, freezing solid and thawing out in the spring. They achieve this amazing feat by increasing their blood sugar levels. This causes them to freeze more like ice cream than an ice cube and prevents any damage to their cells.

Mourning cloaks are one of the species in our Native Butterfly House. This is a favorite summer feature of the Gardens for visitors of all ages, and is dedicated to supporting the entire life cycle of moths and butterflies native to Maine and New England, from egg to caterpillar to moth or butterfly.

After we close the Butterfly House in the early fall, our horticultural team and Lepidopteran Specialist go through the house and inspect all the non-woody plants, looking for chrysalides, cocoons, and mourning cloak adults. These are then removed and refrigerated for the winter, and held at a temperature of 35-40 degrees. In the spring, they will be reintroduced to the House to start our next generation.

Come Visit the Butterflies

If you want to learn more about native butterflies and moths, visit the Native Butterfly House during our regular garden season. 

This 2,160-square-foot hoop house features shade screening and offers visitors the opportunity to observe every stage of the pollinators’ growth first-hand. At any given time, visitors can find mourning cloaks, American ladies, painted ladies, red admirals, black swallowtails, and monarch butterflies in residence. Moth species include Luna, Polyphemus, and Cecropia.

The Native Butterfly House is open mid-June through mid-September. You can typically also find butterflies and caterpillars wild in the Gardens from early June to early October.