Mourning Cloak

I just got back from a delightful dinner with Spo and Someone who are in town from Phoenix. They are off to the opera, and I stopped in at my office (just around the corner from both the restaurant and where they are staying) briefly before heading home. It's raining out and the temperature has gone way up- it's 50° out right now. It's supposed to stay warm through mid-week next week at least.

Warming weather in March in Chicago means a good chance of spotting the first butterfly of the year, which is likely to be a Mourning Cloak. These are cool critters because they overwinter as adults. They keep from freezing by secreting large quantities of a chemical called sorbitol into their body fluids. Sorbitol has some chemical similarities to ethylene glycol, the main component of many kinds of automobile antifreeze. It prevents formation of ice crystals, which would rupture the butterfly's cells, killing it. Instead, the butterfly goes into a suspended animation as the temperature falls. When the temperatures warm up, so do the butterflies, and out they come. Occasionally, you can even see them flying while there's still snow on the ground. A few years back, I wrote an article about them for Chicago Wilderness Magazine. You can read it here.