The following article has been written for the Ripples from the Dunes series, by Kennedy Zittel of the Woodland Dunes, Assistant Naturalist.
The sun is shining, the days are warming up, migratory birds have begun to return…does this mean that spring is finally here? Even though this past winter was not nearly as bad as most Wisconsin winters usually are, I can’t help but wish for long warm days again. And the thought of being able to go kayaking again has really taken over any love that I have for the winter time. With all of these springtime wishes fluttering around my head, seeing another thing actually flutter around my head has me feeling very optimistic. Often called the “harbinger of spring” the butterfly that I saw while walking along willow trail the other day certainly seems like a wonderful sign that spring has finally arrived. Fluttering along the trail was a mourning cloak butterfly. Mourning cloak butterflies (Nymphalis antiopa) are large butterflies that are native to Europe, Asia, and North America.
With no similar looking species around, these butterflies are very easy to recognize. With dark maroon-brown colored wings, a pale yellow edging, and bright blue spots along the yellow edge, these beautiful butterflies get their name from their resemblance to the traditional cloaks worn by those that are in mourning. Though their name derived from such a sad sort of thought, these butterflies bring in happy thoughts of spring and warm weather to come.
These butterflies have such an interesting life cycle, given that they do not (usually) migrate, and instead hibernate here over winter. If given the option, I am not too sure I would choose to stay under frozen leaf litter or in frosty tree cavities, but these butterflies do just that! Mourning cloaks will emerge from hibernation sometimes even before the snow has fully melted, which makes them one of the first butterflies that we see in spring. Their broods will emerge around July, then those butterflies will fly around all summer and fall, hibernate during the winter, those adults will emerge once the snow has started to melt, and then mate in spring. If that sounds like a really long life cycle for a butterfly, you are correct! Mourning cloaks have one of the longest butterfly life spans, given that they can live up to 11 to 12 months.
The immature form of these butterflies is known as spiny elm caterpillars. These caterpillars also have a striking look to them, with black bodies, eight reddish-orange spots along their back, and their entire body covered in short hairs with black spines and white dots. Fully grown these caterpillars will reach around 2 inches in length. Upon hatching the caterpillars will eat the leaves on the plant that they hatched on. A large number of trees and plants have been documented having these caterpillars hatch from, including various willow species, American elm, hackberry, hawthorn, various birch species, wild rose, and poplar trees. The caterpillars will live together in silk nests on the host plant until they disperse before pupation.
The adult butterflies can be found in a variety of habitats, but are most commonly found in hardwood forests. The adult butterflies will feed on sap, ripe as well as fallen fruits, the sugars exudated from aphids, and very rarely they will feed on flower nectar. Though they are not overly helpful in terms of pollinating, these butterflies are wonderful to have around and are certainly a welcomed sight to see in the spring.