The Wooly Bear (Wooly Worm, Woolly Worm)

The wooly bear worm is most famous for its legendary ability to predict winter weather. Also known as wooly worm, woolly worm, black-ended bear, fuzzy bear, or banded wooly bear, the wooly bear worm is actually the caterpillar (larval stage) of the Isabella Tiger Moth. Found throughout the United States, the wooly bear worm caterpillar is more commonly seen in the fall, looking for the ideal place (usually under rocks and inside logs) to hibernate. Once spring comes, the larva awakes to feed once more before entering its cocoon stage. A few weeks later, the Isabella Tiger Moth (a nocturnal yellowish moth with a two-inch wingspan), finally emerges.

While the striped black and brown wooly bear worm caterpillar is the best known, there are actually eight different species of wooly worms in a variety of colors, from light brown to white & black. The colors vary according to the worm’s diet and its age. As wooly worms molt (shed their skin), their color goes from mostly orange to the typical stripped look that is common in late fall.

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Wooly worms can survive extreme cold temperatures because of the bristly hair that covers their entire body and their unique ability to produce an antifreeze-like coating made up of glycerol and other chemicals. Scientists estimate that wooly worms can probably survive temperatures of up to -90oF. In fact, live worms have been found frozen in a cube of ice. Once the ice melted, the worms immediately picked up on their normal activity.

During spring, the female wooly worm lays eggs on a wide variety of plants, including grass, dandelions, clover, and garden vegetables such as spinach and cabbage. When the eggs hatch, the caterpillars feed on the plants.

The wooly worm is also known as the hedgehog caterpillar because of its ability to curl into a ball and “play dead” when picked up. The dual color also makes the worms harder to spot from the air, protecting it from birds and other predators.

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The wooly bear is so venerated that there is an annual Woolly Worm Festival devoted to the wooly worm and its weather prediction prowess.


  1. kathy comello

    Does an all black woolly worm mean a bad winter for 2012 and 2013?

  2. maryv

    found two down here in Houston Texas – both black and very furry!

  3. grace

    ifound one in my back yard and i live in eastern NC. i wonder how well it lives here?

  4. Southern ky lots of full black.will see how this plays out>????

  5. Dee

    We have seen only blond worms in SW PA this year. An article in, however, says the narrower the stripes, the MILDER the winter.

  6. maryb

    saw first one, full black, w/bright yellow/white stripe on sides. summer is over! major drop in temps – always the first sign of summers end.

  7. chey g.

    By this time last year, here in South Eastern Ohio, we had seen many wooly worms, many of which were nearly completely blonde–thus, the mild winter last winter. This year, we’re not seeing ANY wooly worms AT ALL. NONE. NADA. ZILCH. Any ideas? Is this a 2012 thing?

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