Woolly Bears

I did a little online research on Woolly Bears last week after I found so many at SCWMA. I’m sure many of you are familiar with the little black banded fuzzy caterpillars that have the reputation for telling the coming winters weather. While that is fun to speculate, what I found was far more interesting to me. It seems the Woolly Bear caterpillar (Pyrrharctia isabella) larva form of the Isabella Tiger Moth can make its own antifreeze called "cryoprotectants" and chemicals to keep their body fluids from freezing. Wood frogs do this but I had no idea that this caterpillar can do that as well. I haven’t found much about how that happens other than that it does. Currently the ones we are seeing are racing to find a good place to hide for the winter, such as under bark, in crevices and in wood piles.

The other neat thing I learned from an article by Ker Than, in the March 13, 2009 National Geographic News, is it “the first clear demonstration of self-medication among insects”. Elizabeth Bernays of the University of Arizona and other members of her team have discovered that “in the spring, parasitic flies lay their eggs inside woolly bears. When the fly larvae hatch, they feed on the innards of their hosts before exploding out of their abdomens. But when infected caterpillars eat leaves from Senecio genus such as ragwort, the animals get bellies full of drugs called alkaloids.” They don’t know if the alkaloids kill the eggs directly or just boost the woolly bears’ immune system. I thought that was an amazing little unknown fact.

Most of us know them as the fuzzy things that curl up in a ball when we pick them up. They don’t hurt most people but there have been occasion of people who are allergic to the hairs. I wonder if the same people are allergic to wool. Just a thought. I could go on and on about their life history but I just wanted to bring those two unique facts to your attention. They have antifreeze in the winter and can self medicate; both useful abilities.

See more interesting critters at Camera Critter.