Some insects are simply fascinating. Mourning Cloak butterflies are one of them. A beautiful brown-red butterfly with cream colored edges and blue spots on the wings, Mourning Cloaks are often the first butterflies to appear in spring.
Insects use several different mechanisms to survive the winter including migration, communal living, and diapause, which is a long term state of suspension.
Some species, such as Monarch butterflies, migrate, flying south during the cold winter months, and returning when it becomes warm again in spring.
Honey bees and ants live in communities such as hives or colonies. This communal living keeps them warm. Honey bees beat their wings inside the hive, keeping the internal temperatures toasty warm all winter long.
Mourning Cloaks and many other insects use diapause, which occurs when metabolic rates slow for a length of time. This can occur in any phase of insect life. For instance some insects survive winter as eggs, or as pupa, safely tucked away in a cocoon or chrysalis. But Mourning Cloaks hibernate as adults in hollow trees, beneath tree bark, or in other tight places where they can find protection from winter weather. Mourning Cloaks are one of the butterfly species that overwinters in Pennsylvania, and can even overwinter as far north as Manitoba, Canada.
According to Kent McFarland of Audubon, in his article Wintering Butterflies, “The cold itself is not a direct hazard to the butterflies. However, the formation of ice crystals in body tissue is quickly lethal. To keep from freezing, butterflies reduce the amount of water in their blood (White Admiral caterpillars reduce the amount of water in their body by 30 percent) and thicken it with glycerol, sorbitol, or other antifreeze agents. These chemicals function much like the antifreeze we pour into our car radiators. Mourning Cloaks can withstand temperatures down to minus eighty degrees. But it takes cold weather to trigger them to produce these antifreeze agents. If you put a Mourning Cloak in the freezer on a warm summer day, it will quickly die because it lacks any antifreeze.”
Now I find that fascinating.
So in March, as snows begin to melt, and the sun begins to warm the earth, step outside and keep an eye out for the beautiful and fascinating Mourning Cloak butterfly.
when pussy willows show
and daffodils push
through the snow.
the mourning cloaks
warms sister hare,
twixt seasons caught.
Mary Beth Owns
from Be Blest, A Celebration of Seasons