In Praise of Mourning Cloaks

Jennifer NicholsField Notes

Some insects are simply fascinating.  An example of this is the beautiful Mourning Cloak butterfly.  A brown-red butterfly with cream colored edges and blue spots on the wings, Mourning Cloaks are often the first butterflies to appear in spring.

Winter Survival Strategies

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 move to warmer areas in winter to avoid the cold. For instance, Monarch butterflies, migrate, flying to a specific region of Mexico during the cold winter months. Amazingly, subsequent generations of Monarchs return to the same area when it becomes warm again in spring.

Communal Living

Examples of communal living include Honey bees and ants. These insects live in communities such as hives or colonies, which 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.  In contrast, 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 butterflies overwinter in Pennsylvania, and surprisingly can even survive winters as far north as Manitoba, Canada.

According to Kent McFarland of Audubon Society, 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.


Sing Praise,
when pussy willows show
and daffodils push
through the snow.

The sunlight
the mourning cloaks
have sought
warms sister hare,
twixt seasons caught.

Mary Beth Owns
Be Blest, A Celebration of Seasons