Saturday, April 5, 2008

first butterfly: mourning cloak

Another phenologically important event: the first butterfly of the season. It was, as it often is 'round these parts, a Mourning Cloak (Nymphalis antiopa). (Lots of great pictures here, alas that I don't have any of my own.) Another common contender for First of the Year is Milbert's Tortoiseshell, and that's what I thought this one was at first, since they do look rather similar and I am not as up on my butterflies as I would like to be. They're both dark brown/black with light-colored on the wings and a string of blue spots, but the Mourning Cloak is twice as big, and the band is closer to the edge of the wing and is yellow, whereas the Milbert's is orangy.

There still aren't too many obvious flowers blooming yet. Some crocus in people's yard, and I've heard reports of tulips coming up and of Prairie Smoke starting to make buds, and I've seen some dandelions with buds, too. Of course, the catkins on Pussy Willow and birch are actually flowers, and other trees are also starting to put out their inconspicuous version of flowers. But there's still not tons of nectar available quite yet.

Luckily, that's not a problem for the Mourning Cloak butterfly. They feed on rotting fruit and sap oozing from woodpecker holes in trees. This special diet is what allows them to emerge so early in the spring, when it's still barely spring at all and the landscape is mostly brown grass and dirty snow.

Adult Mourning Cloaks are extremely long lived for butterflies--reaching the ripe old age of 10 or 11 months--and they overwinter either as chrysalids or as adults going into a sort of hibernation, tucked under shingles or loose tree bark, or in unheated buildings. When the temperatures rise, the chrysalids hatch and the adult become alive again. I think mine yesterday overwintered as an adult; he looked pretty worn out, and the yellow on his wings had faded to nearly white.

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