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The Mourningcloak Butterfly

March 2, 2020

As I walk along the riparian corridors in the Little Lake Valley, I notice that there is a large maroon or dark brown butterfly with pale-yellow ragged edges flying along beside me. It is not landing for very long making it hard to take photos! This is the Mourningcloak, Nymphalis antiopa, also called the ‘Harbinger of Spring’ because it is often the first butterfly of spring. It is common throughout all of North America. Occurring on mainland England and a rare find in Britain, it is called the Camberwell Beauty.

The name Mourningcloak is due to the appearance of the dorsal surface of the wings, said to resemble the traditional cloak worn by those in mourning, which was sometimes draped over the casket of the deceased. This butterfly lives for about a year and has a wingspan that can reach four inches across. Male Mourningcloaks exhibit territoriality and will pick the highest point for a look-out to watch for other butterflies that enter their territory and will chase them away. According to an article by the Animal Diversity web, which can be read by going to this link ( https://animaldiversity.org/accounts/Nymphalis_antiopa/ ) “They defend areas that are more than 300 square meters  and often rest on dark bark where they enjoy excellent camouflage. Individuals also choose their favorite spots in the direct sunlight, such as leaves or tree trunks…This behavior, along with its dark wing color, enables the Mourning Cloak to absorb as much heat as possible. This is important to individuals living in colder, mountainous areas.”

In the Little Lake Valley, they mate in early spring and then lay their eggs on the twigs and leaves of their host plants, cottonwoods, willows, and wild rose. After hatching, the caterpillar larvae dine on the host plant leaves. The caterpillars eat in a gregarious group on the host plant until it is ready to find a grass blade to hang its chrysalis. Adult butterflies mostly drink sap, but in the summer will drink the nectar of knapweed flower species. Adults will also feed on rotting fruit!

I see many of these lovely ‘harbingers of spring’ as I walk along Davis creek and then Outlet creek, another sign of the early cessation of winter. What will this summer bring for this one species of butterfly? Will I soon be able to find some of its eggs on a willow or cottonwood tree? Every day there is something to observe and ask questions about. 

Photos provided by Peter J. Bremer