Background: My informant is a 50 year old woman from Tennessee. She first heard about the folklore from her father, but has heard it many times anecdotally since.
J: Wooly worms are funny little caterpillars, I’m sure you’ve seen them before. They’re everywhere in the south.
Me: I saw tons of them in Maine when I went to summer camp! So, tell me more about them.
J: Well, I’m no bug expert. I know they’re orange and black, and they’ve got fur! *laughter* I always thought they were funny-looking. They’re usually in the foliage, but some of them come out to uh, say hello at picnics and such. But people think the ones you find in fall can predict the severity of the winter. If the orange band is big, the winter will be mild. A bigger black band means a nasty winter. It’s a common belief.
Me: I think I’ve heard that before. Do you think it’s true?
J: I had some cousins who really thought so. When we were younger we’d go out and look for them and they’d try to make predictions. I was probably only 6 or 7. I didn’t care so much, I just wanted to hold them, and uh, I suppose I didn’t have a good frame of reference back then. I didn’t really know what was a big band or a small band, they usually all looked the same to me. I think I can tell better now. But I’m not sure myself if it’s real. I remember bad winters, but I don’t remember if I saw big black bands on the caterpillars before them.
My thoughts: This superstition is very common, especially east of the American continental divide, so much so that after our conversation I looked it up and saw that a scientist in the 50’s tried to scientifically prove its accuracy. He didn’t ultimately do that great because his sample sizes were too small. Very similar to this practice is Groundhog day, where Punxsutawney Phil looks for his shadow, and if he sees it, it means six more weeks of winter. The difference is that the wooly worm predictions are more localized and personalized, as anyone who finds a caterpillar can make their own predictions. Groundhog day is mostly endemic to Pennsylvania, though even in California some people take it as a prediction for our own winter, which is quite silly. I think the wooly worm predictions have a better chance of being legitimate than the groundhog prediction, though both are ultimately just longstanding and fun folk superstitions.
For more info on wooly worms, see https://www.almanac.com/woolly-bear-caterpillars-and-weather-prediction