The Woolly Bear Caterpillar: Forecasting the weather

woolly BearI grew up hearing folks tell me about forecasting the winter weather by looking at the Woolly Bear Caterpillar. If you know what a Woolly Bear caterpillar looks like you can thank Dr. Howard Curran, his study of them made them famous. The Woolly Bear Caterpillar is really the larva of the Tiger moth. They are a common sight in the fall looking for places where they can curl up and hide for the winter. It is about one and a half inches long with black and brown bristly stripes.
I was always getting conflicting theories on what the colored stripes meant for the coming winter weather. We have seen more of these caterpillars than usual this fall, so I had to look up what they were trying to tell me.

Legend has it that Dr. Howard Curran, a curator at the American Museum of Natural History in NYC decided that he was going to study the woolly caterpillar and see if the folklore was true. It may have been just a fun excuse to get out of NYC and be leaf peepers (city folks who travel to the mountains to see the fall foliage) traveling to Bear Mountain with his wife and friends. They actually called themselves The Original Society of the Friends of the Woolly Bear. Anyway he did actually conduct a study for several years and it turned out the tiny caterpillar did predict with some accuracy whether the winter would be severe or mild. Although he did think his study was too small to say for sure. He said if the brown middle strip was over one third larger than the black stripes at the ends then it would be a mild winter. If the black stripes were wider it would be a severe winter. Most scientists don’t think his theory holds true. But entomologist Mike Peters of the University of Massachusetts explains, “There’s evidence that the number of brown hairs has to do with the age of the caterpillar—in other words, how late it got going in the spring. It does say something about a heavy winter or an early spring. The only thing is . . . it’s telling you about the previous year.”

So you could say that the woolly bear caterpillar does tell you about the winter, but only if you want to know how bad last year’s winter was.  But still, I think the caterpillars guess is that far off than the weatherman’s forecast.

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