By Dan Zarlenga, Missouri Department of Conservation
Photo caption: A mourning cloak butterfly might just be a welcomed sight in the middle of winter. Photo courtesy of the Missouri Department of Conservation
Are you looking for something that reminds you of spring on these short, cold winter days? You might not have to wait until leaves green up and flowers bloom. A hint of spring might just flutter your way in the form of a winter butterfly.
No, it’s not a metaphor. Missouri does have a species of butterfly that sometimes can appear during winter, on one of those sunny, warmer than average days. It’s known as the mourning cloak.
Mourning cloak butterflies may have sad names, but they sport beautiful maroon-brown colored wings laced with contrasting yellow borders. A dark line separates the border from the maroon portion, and in that line blue spots are spaced along the edge of the wing. The butterfly is a colorful sight to see on a drab winter day in the parks, woods, and open areas where they are found throughout Missouri.
As butterflies go, mourning cloaks are long lived, often making it to the ripe old age of 11 months. Considering that most butterfly species only live two to four weeks, that means mourning cloaks are the Methuselahs of the butterfly world! So, with such a long lifespan, it’s inevitable that mourning cloaks must find a way to endure the winter months. As they don’t migrate south like other butterflies such as the monarchs, they must deal with the cold.
The resourceful mourning cloaks hibernate in hollow trees, beneath tree bark, or in other tight places where they can buffer the cold temperatures. Like some other hibernating animals, mourning cloaks can produce an antifreeze agent in their blood that acts much like the antifreeze in a car’s radiator. This keeps deadly ice crystals from forming in their bloodstreams.
In order to fly, these wintertime wonders need to reach a body temperature of about 65F. Usually, butterflies get this warmth from the sun. But mourning cloaks have a special trick up their wings; they shiver, just like we humans. They do this by rapidly contracting their muscles while at the same time barely moving their wings. In just a few minutes, these gyrations can raise the mourning cloak’s temperature 15 to 20 degrees. Add an above average warm day, and they can take flight in the middle of winter!
With no flowers or nectar available, mourning cloaks manage to sip running sap from tree trunks on sunny afternoons, while clinging upside down to the bark.
Perhaps in part, this special ability to survive in winter makes the mourning cloak especially prized among butterfly collectors.
When spring approaches, mourning cloaks do the normal butterfly thing. They mate, after which the females lay their eggs in clumps on the twigs of host plants. Upon hatching, the larvae live and feed communally in a web, then pupate and emerge as adults in midsummer. Though common in Missouri, the mourning cloak can actually be found nearly worldwide!
Next warm day this winter, why not take a hike and see if you might glimpse a mourning cloak. The sight of this butterfly in the middle of winter might take you from mourning the cold to happily anticipating spring.