Live Long and Prosper

During the brief interlude of spring-like weather we had recently, even with patches of snow still on the ground, I spotted a butterfly flitting through the forest. It was a Mourning Cloak (Nymphalis antiopa), named long ago for its dark-brownish black wings colored like the cloak of a person in mourning.

Mourning Cloak are one of the larger butterflies, with a wingspan of four inches (10 cm). Photo by Pavel Kirillov from St.Petersburg, Russia, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0&gt;, via Wikimedia Commons.

How could this butterfly have gone through its life cycle—from egg to larva (caterpillar) to chrysalis to adult—in this cold weather? Well, it didn’t. The Mourning Cloak is one of the few butterflies that overwinters as an adult, taking shelter under bark or in a tree cavity.

How do they survive the cold? They go into diapause, a dormancy many insects undergo in which their systems shut down and their bodies produce glycerol, a kind of antifreeze that protects their vital organs from freezing. Most insects overwinter as eggs, as larvae or as pupae (the resting stage known as a chrysalis in butterflies and as a cocoon in moths).

Mourning Cloaks live long compared to most butterflies—up to 12 months. That they overwinter might be one reason. When the adults emerge in late winter or early spring, they will warm up in sunny patches. They also turn their bodies to the sunlight to absorb heat.

A Mourning Cloak female laying eggs on a Willow leaf (Salix spp.). Notice how camouflaged she is on the underside. Her wings are up when resting, and she blends in beautifully with tree bark. Photo by Jacy Lucier, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0&gt;, via Wikimedia Commons.
 

These butterflies emerge when few flowers are in bloom. Flowing tree sap, with sugars and proteins, are an important early food source for Mourning Cloaks. Later they feed on ripe and fallen fruits as well as the sugary exudate from aphids. They don’t seek nectar as much as many other butterfly species, but I have seen them nectaring on the catkins of Pussy Willow (Salix discolor) and Black Willow (Salix nigra). This is yet another reason to include native shrubs and trees such as these in your landscape. Native willows are an important early pollen source for many native bee species too.

Mourning Cloak males will look for an appropriate territory, a prime location to attract a female. On mating, the female will lay her eggs on leaves of larval host plants: willows, American Elm (Ulmus americana), Hackberry (Celtis occidentalis), ashes (Fraxinus spp.), poplars (Populus spp.), and birches (Betula spp.). They hatch about 12 days later. In early stages the larvae group together in a web, perhaps an adaptation for protection against predators. The caterpillars are black with spines and rows of red dots running down the center of the back, which might be aposematic, a warning coloration. If handled, those spines can sting.

Watch out for those stinging spines on Mourning Cloak caterpillars! It is a good defense for not being eaten by predators. Photo by Hectonichus, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons.

After undergoing five instars (larval growth stages and sheds), the Mourning Cloak spends about two weeks as a chrysalis, before eclosing, or emerging as a butterfly in mid-summer. Adults who lived through the previous winter then die. This new brood is the future of the species.

How can you help this butterfly and other important insects to live long in your yard? Try to garden naturally without using pesticides. Don’t use butterfly boxes. They really don’t work and actually attract hornets, which can prey on butterflies. Allow a “messy” section in your yard, with bark and leaves for overwintering sites. Plant native trees and shrubs such as those mentioned here. We all can do our part to help this striking butterfly and many other important species to prosper.

Published by Jim Sirch

Jim Sirch is the author of Beyond Your Back Door, a weekly blog about nature in your neighborhood. He is also Education Coordinator for the Yale Peabody Museum, a UConn Master Gardener and board member of his local land trust. As a trained naturalist, he brings a deep understanding of geology, plants and wildlife and how they interact within a particular ecosystem. He holds a B.S in Forestry from West Virginia University, a B.S. from Miami University in Science Education; and an M.S. in Environmental Studies Administration from Antioch University. He is also the 2014 Sigmund Abeles Award recipient from the Connecticut Science Teachers and Supervisors Association for outstanding science teaching and professional development.

7 thoughts on “Live Long and Prosper

  1. Thank you. I love this column. I often use it with my homeschooled, 13 yr old daughter as a short reading/vocabulary assignment. She loves it too!

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  2. Thanks for posting about a lesser known butterfly. My father introduced me to butterflies when I was young. We had a big yard and gardens at our house in Monroe. We would catch, preserve, pin and display one or two butterflies of each species that we caught. We also raised several species from caterpillar and then released them back into the yard. A great hobby for a little girl interested in nature. My father still has a large display case of our collection. Mourning cloaks are in our collection. It must be 40 years old now!

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