Sunday, October 21, 2012
They're crossing the road in the area.
The Banded Wooly Bear caterpillar
is the larva of Pyrrharctia isabella, the Isabella Tiger Moth.
The 8 or more species in the United States are called wooly bears because of their long, thick setae (bristles). The caterpillars hatch from their eggs in the fall and overwinter as caterpillars. There are 2 seasons of the Wooly Bears. Those you see crossing the road in the fall hatched beginning in August. I wasn't able to find a definitive reason why they're seen rushing across the roads so often but generally their looking for secluded placed in the fall, under wooded debris where they can spend the winter.
Their found throughout the United States, Mexico and Canada but not elsewhere in the world. They range from temperate to arctic climates. In the winter, the caterpillars can actually freeze solid. "First its heart stops beating, then its gut freezes, then its blood, followed by the rest of the body. It survives being frozen by producing a cryoprotectant in its tissues. In the spring it thaws out and emerges to pupate."
In the coldest regions, growing (and eating) seasons are brief so some wooly bears repeat their life cycle for several years, eating, freezing, thawing, eating again and repeating this cycle. Some are known to live through 14 winters.
The caterpillar normally has a band of bright reddish copper in the middle with the head and tail black, but I have seen individuals nearly completely copper and some all black. Weather folklore lays that you can predict the severity of the winter by the Banded Wooly Bear caterpillar: if the copper band is broad and the black narrow, winter will be mild and, the more black, the more severe the winter. However, larva from the same cluster of eggs show great variation in coloration and the copper band tends to increase with age.
Over the years, I've caught individual Wooly Bear caterpillars to watch them pupate and emerge as moths. I've never been successful. They are often parasitized. It isn't pleasant to see the results so I've stopped making the attempt. I can't say I've ever seen the adult moths. They have a few days, after emerging from the cocoon, to mate and lay eggs before they die. There are 2 seasons: May and August.
You can see Wooly Bears roll up and play dead if disturbed or touched.
Their head is covered in the middle of the ball. Their bristles do not inject anything nor are they designed to break off and irritants. However, they can, just by being bristly, cause irritation and dermatitis so it's not recommended that you let children play with them as I did when I was a kid. If you want to save them on the road, move them in the direction they're going, slide something under them and put them on the side of the road they were headed toward.
There are several Wooly Bear Festivals, somewhat like the Punxsutawney Phil. groundhog event to predict the coming winter weather. Wikipedia list Oil City and Lewisburg, PA as having Wooly Bear festivals, among others. I didn't find anything for Oil City but, in Lewisburg:
Information from Wikipedia, Iowa State University Extension and Outreach and Lewisburg, PA websites. (Please cite your sources.)