16 March 2012

The Mourning Cloak (Nymphalis antiopa)

Photographed yesterday, nectaring on rotten banana flesh that I had smeared on the tree bark.   They were competing with a cluster of flies that had also found the treat.

Mourning cloaks (not "morning cloaks," btw)(and the "Camberwell Beauty" to the Brits) are gorgeous butterflies when seen up close.  I would love to raise some from eggs or caterpillars in order to photograph a newly-eclosed adult, but since these are tree-associated butterflies which use willows, aspens, elms, and hackberry trees as host plants, the eggs and cats have eluded me.  When one of these fellows batted his wings to chase away the flies, he exposed -

- a rich auburn-brown coloration on the dorsum of his wings, surrounded by a yellowish (fading to white) border and a series of bluish submarginal spots.  The dorsal colors may be displayed for wooing mates or for declaring territoriality, but more commonly the butterfly rests with wings folded, because then...

... the coloration provides a stunningly effective camouflage against the typical background of the bark of a tree.  Note in the photo above that the brown color isn't iridescent, but rather muted and patterned like wood.  The scalloped edges of the wing and the marginal band also contribute to the deception.  As you might infer from their coloration, these are butterflies of the woods (or at least the wood margins) which rely on stealth for survival at a time of the year when few insects are available for birds to feed on. 

These are among the first butterflies to emerge in the spring.  They are able to do so because they overwinter not as immatures or pupae, as most butterflies do, but as full-grown adults.  It boggles the human mammalian mind to think that these insects survive way-below-zero temperatures hiding under the bark of trees, under leaves, or in woodpiles.  Clearly they have some effective antifreeze or other defence against cellular disruption.

When they emerge on the first warm days of spring, they need sugar for energy, but there are typically no flowers for them to nectar on.  So they find nutrition in the seeps of tree sap at sites of injury (woodpecker holes, storm trauma).  But they're not particular, and if an obliging human happens to take an over-ripe brownish-black banana and smear it on a tree, they will quickly use that resource (fwiw, I was pleased to note that this banana was still attractive to them a day after I placed it out, despite having desiccated overnight).

Addendum March 24:  I am so jealous of SWBA member "Alisha," who posted the following photo at the organization's butterfly sightings webpage yesterday:

"I saw a Mourning Cloak 3 days ago along this trail [McMillan Marsh, Wood County], and today when hiking back through found these Mourning Cloak eggs. I've got them safely set up to hatch and am looking forward to my very first time in bringing a complete life cycle."
There must be over a hundred eggs in that cluster.  I'll be out looking for eggs as soon as I'm ambulatory.


  1. your blog is always full of interesting articles. =]

  2. Apparently bumblebees can start a chemical reaction in themselves to warm themselves up. I think of them being a bit like a glowstick. Perhaps butterflies have a similar thing?

    1. Aaah, just checked. Thats not true. I must have been thinking of another insect. I wonder which one?


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