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What Does the Woolly Bear Caterpillar do in Winter?

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Woolly Bear Caterpillar (Photo: Graftendno1, Flicker Sharing).

How the Woolly Bear Caterpillar Survives the Cold

Have you ever wandered around a parking lot, sidewalk, or trail in the fall and seen a Wooly Bear caterpillar? They're the familiar fuzzy orange and black caterpillars that everyone dodges stepping on and that kids love to pick up and play with.

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Adult male Isabella Tiger Moth (Photo: Seabrooke Leckie, Flicker Sharing).

These fuzzy wee beasties are technically called the "Banded Woolly Bear" and they are the larval form of the Isabella Tiger Moth (Pyrrharctia isabella). The adult moth isn't very striking. It has golden-brown wings. They also have faint darker brown lines on their wings and the females have a pinkish-orange hind wing. The nice thing is that the caterpillar isn't a crop pest and mostly feeds on common deciduous forest trees such as elm, ash, low growing herbs, and other forest plants (they're not very picky and tend to sat away from gardens).

THE WOOLLY BEAR MYTH

Now most people have heard the myth that the woolly bear caterpillar can predict winter's length and intensity based on how much black is on them or how big the orange band is around their middle. This is really an old wives tale because as the caterpillar grows, during each molt (or shedding of its skin) the fuzzy black tips become less and less pronounced and the orange band grows. So, the caterpillar color barometer is really subjective based on which one you found and what molt phase it's in.  Not very reliable if you ask me.

IC_Pyrrharctia_isabella_caterpillar

Adult woolly bear caterpillar (Photo: Wiki Commons)

So, seeing all those fuzzy cute woolly bear caterpillars got me to thinking and wondering, if they don't predict winter, what exactly do they do to over-winter? Where do they go? How do they survive? Seeing as they can't crawl very far they have to have some strategy to make it through freezing conditions. After all they are found all the way from the Arctic to North America and Mexico.

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