Where did all the Fermilab butterflies go?

I think about one week ago I saw perhaps the last butterfly (for me) of 2001, a yellow Clouded Sulphur. There are many different ways that species survive the winter, but each species uses just one (or rarely two) method. Some, like the Monarchs and Red Admirals, have flown south.

Right now, sitting under dried leaves on the ground around the edge of the woods, tiny Great Spangled Fritillary caterpillars are hibernating. And tiny Viceroy caterpillars are sitting on willow bushes all through the winter. It is amazing that they survive! Common Wood-Nymph caterpillars also overwinter after hatching from the eggs, and since they would be in the prairie, I am afraid that our prairie fires must kill many of them.

In the woods, adult Question Marks, Commas, and Mourning Cloaks are sitting in hollow cavities in dead trees or in other protected places. I have seen them come out and fly during warm days in March. Tiger Swallowtails and Black Swallowtails overwinter in the chrysalis and emerge in May or June. I kept a Tiger Swallowtail chrysalis outside in a box last winter; the adult emerged on May 18 and is the one that I photographed then.

Exactly how some butterflies overwinter is not known; there are still some secrets to be discovered. How they overwinter is one of the really interesting and amazing things about insects.

Tom Peterson