Mourning Cloak: Flutter on Snow
The Great Outdoors | March 1, 2020
By Jackie Scharfenberg, Forest Naturalist, Wisconsin Department of Natural Resources
Last fall, I found the perfect spot under some loose tree bark to hibernate away winter. The warm spring sun woke me up, but wait! Look! There’s still snow on the ground – how disheartening! I think I’ll flutter around to see if any other mourning cloak (Nymphalis antiopa) butterflies awoke. Will you help me in my search?
So you don’t confuse us with those other overwintering butterflies (the red admirals, commas and tortoiseshells) let me describe our appearance. Our wingspan measures three-four inches making us a larger butterfly. Our upper wings sport a rich red-brown color with a yellow band along the jagged margins and bright blue spots next to the yellow band. When we close our wings, our mottled brown under wings have dull white borders that camouflage us with tree bark. We belong to the brush-foot butterfly family which all possess small, hairy front legs making it look like we only have four legs.
We prefer to live in wooded areas near water, but we may also reside in parks, yards, forest openings, meadows, and swamps. You can find us throughout most of North America (including all of Wisconsin) and Eurasia.
Our Life Cycle
In April and May, our males locate sunny open spots where they show off to entice the females to mate with them. After a brief aerial courtship, the females lay two to three batches of 30-50 eggs each in masses around tree or shrug twigs. These twigs may grow on elm, willow, poplar, hackberry, and birch trees, which provide food for the caterpillars. After ten days the eggs hatch.
Following mating and laying eggs, the adults die at the age of ten to eleven months. This makes us one of the longest lived butterflies.
The caterpillars stick together in a silken nest and eat young tree leaves. The caterpillars’ black bodies come covered with short hairs and black spines. A line of eight reddish-orange spots runs down the center of their backs. Their looks warn predators to stay away. After molting five times, they reach full size – about two inches. When threatened or disturbed, a mass of caterpillars shakes in unison to frighten off a potential predator like a bird, assassin bug or beetle.
When they get ready pupate, the caterpillars disperse. You know the old saying, “Don’t pupate where you last pooped.” After finding a spot under an overhang, a caterpillar forms a spike-covered, brownish chrysalis. This chrysalis will become a butterfly in 10-15 days. This takes us into mid-June and July.
Don’t search for us butterflies on flowers, since we rarely feed on nectar. We prefer to dine on tree sap (a spring stable), overripe fruit, and the sugary stuff exuded by aphids. After feeding awhile, we find a protected spot to go into a summer hibernation called aestivation to avoid the season’s heat. We emerge in fall to forage for several weeks before we settle in for winter hibernation.
Forget those robins! Look for us mourning cloak butterflies as a sign of spring’s return!