The Myth of the Woolly Bear

Legend holds that the length of a woolly bear caterpillar's color bands can be used to forecast how severe the winter weather will be. The myth dates back to colonial American folklore but was popularized by a 1948 study. SciFri finds out if there's any truth to the lore, and what the caterpillar's fuzzy bristles are really used for.

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JOHN DANKOSKY, HOST:

And it's time for the Video Pick of the Week. And joining me now is video producer Luke Groskin. Hello there, Luke.

LUKE GROSKIN, BYLINE: Hi, John.

DANKOSKY: So what do you got for us this week?

GROSKIN: Well, the video pick this week is the myth of the woolly bear.

DANKOSKY: The woolly bear?

GROSKIN: Yes. And we're not talking about the ursine type of bear, like a grizzly o black bear. We're talking about the caterpillars.

DANKOSKY: The little fuzzy guy, he's sort of rust-colored, kind of black?

GROSKIN: Yeah, the ones that people in the U.S. can see crossing roads and trails, you know, in the fall.

DANKOSKY: OK. So why are you so interested in the woolly bear?

GROSKIN: So there's this myth. Have you heard this myth?

DANKOSKY: Well, having something to do with the weather. They can predict the weather?

GROSKIN: Yes. So the myth is that the rust-colored bands that's on the back of the woolly bear, that that - that the width of that can actually help you determine how severe the weather will be. So if it's wider, it will be a bad - it will be a good winter. If it's smaller, it's going to be a more severe winter.

DANKOSKY: Sort of like an insect Punxsutawney Phil.

GROSKIN: Yes. Exactly like the groundhog, except kind of forecasting into the winter instead of looking out back at it and forward. Anyway, so the woolly bear is - this myth has been around since, you know, the colonial times. But in 1948, this curator of entomology from the American Museum of Natural History, Dr. Howard Curran, he did a little study. He went out to Bear Mountain, New York, and he counted the woolly bears, the bands - the brown bands of the woolly bear there. And he counted about 15 different specimens, and he made a prediction. And it got picked up by the national press. He had a reporter come with him, and it became a very popular myth. And so it kind of spread around the country. And even today, there are places in the country that celebrate the woolly bears prognostication and have festivals.

DANKOSKY: Now, I got to say, Luke, I am no scientist, but 15 woolly bears, that doesn't sound like a real great study.

GROSKIN: Yeah. It's not exactly scientifically valid. But, you know, the researchers that I spoke to, none of them were willing to go on the record as saying that it wasn't true. Nobody was willing to say it wasn't true. Science is still out on that. But that doesn't mean that there's not really fascinating things about this species.

DANKOSKY: Well, and that's what's really cool. Before we run out of time, these woolly bears, they have all this fur on them. So what do they use this fur for?

GROSKIN: So it turns out that this fur isn't to protect them from cold weather. It's actually to do the opposite. It actually helps them to freeze. Now if you want to find out how it actually helps them to freeze, you have to go on to sciencefriday.com and watch the myth of the woolly bear. And you'll learn all about woolly bears and hopefully learn to appreciate them as much as many people do.

DANKOSKY: So you can go on there and take a look. These little guys, they freeze over winter. This is amazing.

GROSKIN: Yeah, they hibernate like bears. But unlike bears who stay nice and cozy in their den, they stay cold. They stay frozen. Now it's not their entire body. It's not their cells. It's the spaces between their cells, their hemolymph and areas like that. They want to keep the freezing away from their cells, and they stay nice and protected by these things called cryoprotectants. And it's the same stuff that you put in your car - or you used to put in your car engine, antifreeze. And it's a chemical called glycerol.

DANKOSKY: OK. So, well, we'll learn more if you go to sciencefriday.com. You can find out more and take a look at the Video Pick of the Week. Thanks so much for stopping by, Luke.

GROSKIN: Thanks, John.

(SOUNDBITE OF MUSIC AND SHOW CREDITS )

DANKOSKY: I'm John Dankosky.

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