Will it be a harsh winter?

How does folklore begin? Surprisingly, its roots are usually formed in fact rather than in fiction. Take the legend of the woolly bear: the brown and black caterpillar credited with the power to predict upcoming winter weather. Is it true? And who discovered it?

I feel particularly privileged to share the tale since it originates in my neck of the woods: Bear Mountain State Park, about a 15-minute drive from my home. As legend has it, in the fall of 1948, Dr. C. H. Curran, curator of insects at the American Museum of Natural History in New York City, took his wife 40 miles north of the city to Bear Mountain to check out woolly bear caterpillars. It was the first of what was to become an annual trek.

While there, he collected as many caterpillars as he could, determining the average number of reddish-brown segments on the little buggers, and playfully forecasting the coming winter weather through a reporter friend at The New York Herald Tribune. Of course the critters are presumably named for their fuzzy appearance, and the fact they were originally studied at Bear Mountain, but these immature larva of Pyrrharctia isabella, the black-spotted, orangey winged Isabella tiger moth, are actually known to roam (and eventually flutter) in parts as wide-ranging as Southern Canada and northern Mexico. Yet the moth version of the species seems far less intriguing than the Rasputin-esque caterpillar.

In fact, Dr. Curran was so intrigued by his first experiment with the bristled crawlers, he continued it over the next eight years, attempting to prove scientifically a "weather rule of thumb" with the thumb-sized weather forecasters. His highly publicized efforts made the woolly bear the most recognizable caterpillar in North America.

Woolly bears, like other caterpillars, hatch during warm weather from eggs laid by a female moth. Mature woolly bears search for overwintering sites under bark or inside rock or log cavities, and when spring arrives, they spin gossamer cocoons and transform, reinventing themselves even more completely than Madonna, and emerge as full-grown moths. Usually, the bands at the ends of the caterpillar are black, and the one in the middle is brown or orange-brown, giving the woolly bear its distinctive striped appearance.

As legend has it, the wider that middle brown section is (the more brown segments), the milder the coming winter will be. Narrow brown bands predict harsher winters. But is it true?

According to the Farmer's Almanac: "Between 1948 and 1956, Dr. Curran's average brown-segment counts ranged from 5.3 to 5.6 out of the 13-segment total, meaning that the brown band took up more than a third of the woolly bear's body. As those relatively high numbers suggested, the corresponding winters were milder than average.

But Dr. Curran was under no scientific illusion: He knew that his data samples were small. Although the experiments popularized and, to some people, legitimized folklore, they were simply an excuse for having fun. Curran, his wife, and their group of friends escaped the city to see the foliage each fall, calling themselves The Original Society of the Friends of the Woolly Bear.

Thirty years after the last meeting of Curran's society, the woolly bear brown-segment counts and winter forecasts were resurrected by the nature museum at Bear Mountain State Park. The annual counts have continued, more or less tongue in cheek, since then."

Yet Mike Peters, an entomologist at the University of Massachusetts, suggests there could, in fact, be a link between winter severity and the brown band of a woolly bear caterpillar. "There's evidence," he says, "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. The [band] does say something about a heavy winter or an early spring. The only thing is . . . it's telling you about the previous year."

So the little critter I caught up with on my back patio, pictured above, seems to have a narrower brown center. According to folklore, that means a harsher winter to come. Yet we know last winter was one of our harshest ever, so I'm sticking with science and saying that little guy's narrow band of brown is a testament to the past, and not a harbinger of impending deep freeze.

If that's the case, then we've come full circle. We're back to that age-old question: What will the weather be like this winter? Who knows! Chalk it up to yet another mystery in the universe. Meanwhile, I'll think warm thoughts as I watch my little woolly bear snuggle between the stones of my retaining wall.