Woolly Bears

(This column was first published in the November 10, 2003 issue of The Buffalo News.)

I begin this column with a question: How many of you readers know anything about the Isabella tiger moth?

Not many, I suspect, although this is a rather common, medium-sized moth. It has yellowish-orange and cream-colored wings spotted with black. The colors of its thick body are similar to those of its wings.

Ah, but you do know about the larva of this moth. It is easily the best known of all caterpillars, the famous (or infamous, depending on its prediction) woolly bear.

The woolly bear, black-ended bear or in the South woolly worm is a bristly little sausage an inch or so in length. It does in fact feel woolly to the touch. Its mid-body is orangish-brown in color but its ends are, as that second name suggests, black.

What makes the woolly bear so famous is the variation in the amount of black at its ends compared to the chestnut of its mid-section. The amount of black, according to the old wives' tale, correlates with the severity of the coming winter: more black, harsher weather.

It turns out that this prediction was investigated by C. H. Curran, curator of insects at the American Museum of Natural History in New York City. Each fall from 1948 to 1956 Dr. Curran and his wife traveled north from the city to Bear Mountain State Park where they counted the segment colors of woolly bears. During that period the number of brown segments averaged about 5.5 out of 13 and those rather high numbers predicted mild winters. Sure enough, those winters were milder than average and the New York Herald Tribune trumpeted those "scientific" findings.

But as one writer has told the story: "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, who called themselves The Original Society of the Friends of the Woolly Bear, escaped New York each fall for the glorious foliage and the meals at the posh Bear Mountain Inn. The naturalist Richard Pough was a member, as was Kim Hunter, the actress who starred in the movie Planet of the Apes."

Despite that, the prediction caught on with the general public. It is today about as widely believed as that other, equally-nonsensical forecast, that of the Farmer's Almanac. (I note, however, that the almanac may have joined the modern world to base its predictions on weather information provided by trained meteorologists.)

Like the groundhog, the woolly bear continues to enjoy its reputation through weather predictions not only from Bear Mountain Park but also from a Woolly Worm Festival each Fall in Banner Elk, North Carolina. There a race determines a champion woolly bear and that single caterpillar is examined to determine the nature of the upcoming winter.

As you can see, I'm with the doubters. Charles Covell says in the Peterson Field Guide to Moths: "Colors change as caterpillars molt to successive instars, becoming less black and more reddish as they age. Thus differences in color merely reflect age differences...and are not a reliable indicator of the severity of the winter to come."

And according to Mike Peters a University of Massachusetts entomologist, "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. [Thus it] does say something about a heavy winter or an early spring. The only thing is, it's telling you about the previous year."-- Gerry Rising