Friday, November 6, 2020

The Woolly Bear’s Winter Weather Prediction 

woolly bearMany of us have heard of the story that a small, fuzzy caterpillar Called the Woolly Bear (aka woolly worm or hedgehog caterpillar) carried the prediction of the coming winter on its back.  Whatever name you choose to call them, these cuddly looking caterpillars are often found in the autumn after they have left their food plants, a variety of grasses and weeds, in search of a sheltered spot where they can hibernate as larvae for the winter.

According to folklore, the amount of black on the woolly bear in autumn varies proportionately with the severity of the coming winter in the geographical area where the caterpillar is found.  The longer the woolly bear’s black bands, the longer, colder, snowier, and more severe the winter will be.  Similarly, the wider the middle brown band is associated with a milder upcoming winter.  The position of the longest dark bands supposedly indicates which part of winter will be coldest or hardest.  If the head end of the caterpillar is dark, the beginning of winter will be severe.  If the tail end is dark, the end of winter will be cold. In addition, the woolly bear caterpillar has 13 segments to its body, which traditional forecasters say correspond to the 13 weeks of winter.

As with most folklore, there are other versions to this story.  The first one says that the woolly bear caterpillar’s coat will indicate the upcoming winter’s severity.  So, if its coat is very woolly, it will be a cold winter.  The second version uses the woolly bear caterpillar’s direction of travel.  It is said that woolly bear’s crawling in a southerly direction are trying to escape the cold winter conditions of the north and woolly bear’s crawling on a northward path would indicate a mild winter.

Though it is widely believed that the woolly bear caterpillar can predict the upcoming winter’s severity, the truth is that this caterpillar has no predictive ability to what the upcoming winter has in store for us.  The woolly bear caterpillar’s coloring is based on how long caterpillar has been feeding, its age, and species.  The better the growing season, the bigger it will grow.  This results in narrower red-orange bands in its middle.  It is the width of the banding that is an indicator of the current or past season’s growth rather than an indicator of the severity of the upcoming winter.  Also, the coloring indicates the age of the woolly bear caterpillar.  The caterpillars shed their skins or molt six times before reaching adult size.  With each successive molt, their colors change, becoming less black and more reddish.  

The truth about the woolly caterpillar’s coat, this is how Mother Nature helps it survive winter.  The fur is called setae and it isn’t there to protect them from the cold weather.  Instead it actually helps them to freeze more controllably an amazing natural adaptation to survive the Winter.  Once settled in the spot they have chosen for the coming Winter, the caterpillars hibernate, creating a natural organic antifreeze called glycerol.  They freeze bit by bit, until everything but the interior of their cells is frozen.  These interior cells are protected by the hemolymph.  Woolly bears can – and do – survive to temperatures as low as -90oF.  This ability to adapt to cold is found in the Arctic, where the woolly worms live in a strange state of suspended animation.  Most caterpillars live for two to four weeks before becoming moths.  The Arctic woolly bear will spend at least 14 years in the process.  The woolly bear caterpillar has even been known to survive an entire winter completely frozen in an ice cube.

As far as the woolly bear caterpillar’s travel goes, they are simply moving about in search for that perfect spot to curl up and spend the Winter usually under bark, a rock, or a fallen log. 

There is great interest in its caterpillar or larva stage, however very few people know what it grows up to be. This fuzzy, 1½ inch caterpillar becomes an Isabella Tiger Moth.  After wintering this caterpillar awakens on a warm spring day and continues to feed.  Shortly after the woolly bear forms a cocoon and pupates. In about two weeks, an orange-yellow moth with 1 ½ to 2-inch wingspan emerges.  The wings lack distinctive markings but the abdomen is spotted with three longitudinal rows of small black dots.  These moths are active at night throughout summer months as they lay eggs for the generations to come.  

We believe this folklore is not to mislead people as to the ability of a small caterpillar to predict the coming winter but to stir curiosity and bring awareness to the life of these amazing little creatures.  The photo above was taken in the Adirondacks on October 9.  If we were to go by this creature in predicting the coming winter here in the mountains, this little guy is predicting this winter will start out cold with lots of snow, then become mild and end with colder temperatures and snow.  Being mountain people, what we do know for sure is that there will be snow and it will get colder.  Time for bundling up and snow removal of all sorts.


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Jackie Woodcock was born and lives in the Adirondack Mountains. She is an apiarist, lepidopterist, conservationist, teacher, writer, artist, and a co-owner of SkyLyfeADK. You can find her SkyLyfeADK on Instagram and Facebook.

22 Responses

  1. Penny Overton says:

    I love this story because it goes in detail about the life of a caterpillar and a moth because I didn’t know about them. I love ur choice of a good story.

  2. Stacey says:

    I had one by my door so I just picked it up with a napkin and put in the flowers that I have it went straight to them….I have a cool video I toke..

  3. Charlie S says:

    Prediction of weather by observing colors on a caterpillar! Interesting! I saw, and plucked two of these little fellers from the road in rural Otsego County just two Friday’s ago near Hartwick. I saw some others that were flattened from cars passing. I cannot save the world but I saved two Woolly Bear caterpillars on this day!

  4. Frankie Cousin says:

    I believe God has giiven us indication through His creation that will help us to predict weather and foretell other occurrences in our life here on earth.

  5. Nora says:

    Loved this article and had to share with my friends on FB. Thank you Jackie Woodcock for an excellent and very informative article .

    Chestertown, New York

  6. Greg Keefer says:

    Articles like this are awesome. Keep them coming.
    I try to avoid running over them while driving if I safely can.

  7. Diane sehlin says:

    I found a little one in september. Was about the same color as this one.

  8. Gary schaible says:

    I heard this story before from my grandparents. Every year as I go down the highway I look for them slowly worming there way across the road and try to see what their color happens to be.
    This must be a very bad year because most of them that I have seen is squashed. They need to move faster. LOL

  9. Linda Farabaugh says:

    I live in Ohio. The wooly worms I have seen are mostly all black. So I guess that means a bad winter?

  10. Wanda Moravec says:

    I think that was absolutely great.

  11. Alyssa says:

    They may not be able to predict the weather, but they sure are cute. ?

  12. Betsy Lynne Lindstedt says:

    I loved your article about the woolly Bear caterpillar. Nice to know about the facts on the meaning of the stripe on the caterpillar’s body. I have enjoyed seeing them every fall since I was a child. My hometown is in the Finger lakes region near Cayuga Lake in upstate New York.

  13. Mary Lou Diorio says:

    Lovely read about this interesting insect. I love knowing about the nature around me and this was delightfully written, so I read it to its end.
    Thank you.

  14. Mark says:

    What about cows that are laying down? Does that mean rain, or no rain??

    • Anita Dingman says:

      We used to live beside a pasture with a lot of cows. Yes, cows lying down DOES mean that it will rain.

  15. Linda Kloczkowski says:


    Such a whimsical and interesting article on the Woolly Bear Caterpillar!! I learned a lot from your writing this. I actually found an all-black with just a hint of red-orange woolly last month!! Thanks for sharing the info.

  16. Peter ODell says:

    very interesting and informative — I always enjoy these little creatures in my yard and always protect them from my rake or mower etc.

  17. Joe benanti says:

    Always loved these weather predicators!!!

  18. Anita Dingman says:

    Are they ever albino? I saw one last summer that was all a cream/white color.

  19. barbara clem says:

    barbara clem, I enjoyed this informative article. Well written. As a retired school teacher , this is the type of article I would print and have in my classroom for my students that could and would enjoy and learn interesting facts .

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