Woolly Bears: A Sign of Autumn

No, Woolly Bears aren’t large, furry mammals like black, brown, panda, or polar bears.

The Woolly Bears I’m referring to are insects.

They’re the adorably fuzzy black-with-rust-band caterpillars that appear throughout the U.S. and parts of Canada and Mexico every autumn, usually in September. I remember being delighted spotting them as a child growing up in western Washington state. If I touched them while they were still on the ground, or gently picked one up to hold in my palm, they would slowly curl into a tight, furry ball. Once they felt safe in my hand, though, they would open up and start crawling again. They have fourteen tiny “feet” that tickled ever-so-lightly when moving across my skin.

I don’t remember having a particular name for them then. I just called them caterpillars.

Now I know they have the perfect name: Woolly Bears. Their scientific name is Pyrrharctia isabella, and in the spring they become the beautiful orange Isabella Tiger Moth.

Even more than the cooler temperatures and shorter days, for me it’s leaves turning color and these banded caterpillars appearing that announce the arrival of autumn. (This year, autumn officially starts tomorrow, September 22, 2021.)

As the boys and I were finishing our walk this morning, I saw this Woolly Bear crossing the road, right on schedule.

woolly bear caterpillar crossing a sandy road
A Woolly Bear caterpillar making a hazardous journey.
dog nose next to woolly bear caterpillar on road
Conall – the woolly Malamute – getting a closer look.

Most mornings I take my dogs for an easy-paced stroll of a couple of miles through the neighbors’ fields and forests. Finn is doing great, with a slight head tilt the only sign he was dealing with vertigo a few weeks ago. But he’s an old man, so we go at an old man’s pace. I rather enjoy that pace because I have more time for photos. We go early, maybe an hour after sunrise, so there’s often some mist on the ponds, or fog hovering over the fields, and on clear days, early sunlight filters through the leaves and limbs of the tall maples and birches.

mist on pond, geese in grass, fall color in trees
Mist rising from a pond, a flock of Canada geese resting on the grass, and a tinge of fall color in the trees beyond. September 20, 2021.
round hay bales in plastic beside a field of grass and clover
Fog slowly burning off the fields of grass, clover and another plant with white flowers I can’t identify. Round hay bales from an earlier cutting await transport, wrapped in plastic but still giving off a powerful, sweet scent of wet mowed grass when I walk by. September 18, 2021.
clouds and sky reflected on pond surface
Reflections on a pond. September 16, 2021.
dogs on forest path, morning sun through maple and birch trees
Early morning sunlight breaking through maple and birch trees, highlighting dogs and path.
September 20 2021.

The leaves are starting to turn in Vermont. One young maple we pass regularly, deep in the woods, is already entirely on fire with brilliant vermilion leaves.

path through woods with bright red maple tree
An early-changing maple. Be early, be seen! September 20, 2021.
close-up of red maple leaves
A close-up of those spectacular maple leaves.

The chokecherry trees along the fields’ edges started their transition weeks ago, turning a deep reddish purple, but their leaves are small and they’re a fairly short tree, so their visual impact is muted. It’s the older maples and birches, rising high above their neighbors, that will put on the real show over the coming weeks.

Closer to the ground there’s plenty of autumn to see. While the abundant Goldenrod and Milkweed flowers have recently gone to seed, Asters – both white and purple – continue to add brightness to the landscape, blooming abundantly on the edges of woodland paths and roads.

purple-stemmed aster flowers, also purple
Purple-stemmed Aster flowers , battered after a drenching overnight storm. September 16, 2021.
flat-topped white aster flowers
Flat-topped White Aster blooming in the woods. September 21, 2021.

Tourists who come to New England to view the autumn colors are referred to leaf peepers.

Well, I’m not a tourist in Vermont, but I’m such a recent transplant that I will fully embrace my leaf peeping status this autumn. I’m looking forward to the next several weeks, watching the hillsides all around me change until they’re exploding with variations of yellows, oranges and reds before finally dropping their leaves for winter.

dog on path through tall birch and maple trees
Conall leading the way through a bower of tall white birch and maple trees. September 21, 2021.
cattail, trees, pond with mist
Cattails are another sign of autumn. This one has become my favorite because it stands tall and proudly alone, several feet away from the pond’s banks where the rest of its kind grow in groups. September 20, 2021.

Once all the leaves are on the ground, dried and crunching underfoot as the air turns frigid and smells of snow? That, I’m told, is called “stick season” in Vermont. The transition from fall to winter.

But wait, what about that adorable Woolly Bear caterpillar I mentioned at the start of this post?

You know me. Intrigued by the one I saw this morning, I couldn’t resist learning more about them.

Also known as the Woolly Worm in the south (though decidedly not a worm), it turns out Woolly Bears are so heavily associated with autumn that here in the Northeast they have inspired winter-weather-predicting folklore going back generations. And they have a strange and fascinating sort of anti-freeze in their blood that allows them to withstand incredibly cold winters in a state of hibernation.

They’re also known as the Hedgehog Caterpillar for their habit of curling into a tight ball as a defense mechanism, something I found charming as a young girl.

Woolly Bear caterpillars hatch in summer from eggs laid by the female Tiger Moth. In autumn, they leave the plants they’ve been munching on all summer (grasses, weeds, nettles, dandelions) and are seen crossing roads and sidewalks in search of a winter hiding place under bark or in the cavities of rocks and logs, where they hibernate. The following spring they’ll spin a fuzzy cocoon – I remember as a child seeing the cocoons on the side of our house, snug in corners, usually on brick, where they were well protected from weather – eventually emerging as a Tiger Moth.

What follows is information about Woolly Bears found on the U.S. National Weather Service website. Yes, the Weather Service, proving the strength and longevity of the folklore about Woolly Bears predicting winter weather.

According to folklore, the amount of black on the woolly bear in autumn varies proportionately with the severity of the coming winter in the locality 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 2 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 final version deals with the woolly bear caterpillar’s direction of travel. It is said that woolly bears crawling in a southerly direction are trying to escape the cold winter conditions of the north. On the other hand, woolly bears crawling on a northward path would indicate a mild winter.

Even though it is widely believed that the woolly bear caterpillar can predict the upcoming winter’s severity, the truth is that this caterpillar can’t predict what Old Man Winter has in store for us in the upcoming winter. The woolly bear caterpillar’s coloring is based on how long the caterpillar has been feeding, its age, and species. The better the growing season is, the bigger it will grow. This results in narrower red-orange bands in its middle. Thus, the width of the banding 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.  In addition, there are approximately 260 species of tiger moths (the adult of the woolly bear caterpillar) in North America, and each species has slightly different color patterns and hair coverings. As a result, some of the color and hair variations that we see each fall are a result of these different species.

close-up of woolly bear caterpillar
Woolly Bear caterpillar.

As far as the story 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. Here is something truly remarkable. Once settled in, the caterpillars hibernate, creating a natural organic antifreeze called glycerol. They freeze bit by bit, until everything but the interior of their cells are frozen. These interior cells are protected by the hemolymph. Woolly bears can – and do – survive to temperatures as low as -90F. This ability to adapt to cold shows up particularly in the Arctic, where the woolly worms live in a strange state of slow motion. Most caterpillars live for two to four weeks before becoming moths. The Arctic woolly worms, however, 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.

This myth [of predicting winter] has been around since colonial times. However, it grew in popularity after Dr. Howard Curran (curator of entomology from the American Museum of Natural History) did a small study in 1948. He went out to Bear Mountain, New York with a reporter, his colleagues, and their wives. He counted the brown bands on 15 different specimens. He then made a prediction for the winter. This news story was published in the New York Herald Tribune. It was picked up by the national press and the rest is history.

National Weather Service

Feature photo: Conall waiting for me and Finn to catch up before leaving the fields for home. He’s wearing his orange Do Not Hunt Me vest because, well, it’s hunting season again. At least it’s not legal to hunt wolves in Vermont, so it’s slightly better than Idaho, but not much. Behind Conall, chokecherry leaves make a red band close to the ground while the taller maple is just showing hints of fall color. September 20, 2021.

32 thoughts on “Woolly Bears: A Sign of Autumn”

  1. But he’s an old man, so we go at an old man’s pace. Hey! Hey! Hey! No need to get snippy, Missy. 😁 Beautiful post with fabulous photos that really capture the changing of seasons, something not really much of deal in SoCal. I, too, always like Wooly Bears when I lived in places they inhabited. As the article noted I had heard the thickness of the Wooly Bear “fur” foretells the severity of a coming winter but I never could see a difference. Maybe a close inspection of a Wooly Malamute would be a better predictor? Has Conall or Finn demanded their first pumpkin spice Milk Bone of the season?

    Liked by 2 people

    1. Are you old…? 😉

      Thanks; it’s fun to photograph the changes in seasons, especially in a place like Vermont where the transition from summer to fall is so spectacular. I can hardly wait for the real show to arrive! Proud leaf peeper, here!

      Conall agrees about predictions, that his woolly fur is a better predictor of upcoming winter weather than some silly caterpillar’s. I’m just now removing all the thick undercoat (and some mats) from last winter’s thick coat, and the next undercoat is coming in! A never-ending ordeal.

      Finn says bring on the pumpkin spice treats! He LOVES pumpkin (he gets a dollop of of it on his kibble most days). Conall, not so much. Those northern breeds; they’re all about fish and meat, forget the veggies. (But he does like broccoli.) Please make sure Max gets an autumn treat, courtesy of Finn & Conall, whether pumpkin flavored or something more enticing to his palate. Woof!

      Liked by 1 person

      1. Am I old? I guess it is relative. Let’s just say that Google was named after my age. My birth certificate says “expired.” Moses was my high school class president. And so on infinitum. But, hey, still vertical and that’s better than the alternatives! Pumpkin spice dog cookies all around! Broccoli for Conall.

        Liked by 1 person

  2. Aren’t those fuzzy little Wooly Bears a wonderful gift from nature. I wonder what they’re predicting about this winter. As for Conall’s curiosity, I think it’s adorable. His cute fuzzy face calls for a pat. Love your photography Rebecca! Are you using a phone or a camera? I recently pulled out my “real” camera after a long while.

    Liked by 1 person

    1. Thanks, Shelley! Conall is the best, always showing me creatures I might not otherwise notice, although in the case of the Woolly, I was the first to notice.

      I’m using my Pixel3a phone camera for all my photos. It’s lightweight, fits nicely in a front pocket on my running/hiking pack, and since I carry the phone for emergencies anyway, it’s always with me. I do, though, edit my photos in Adobe Elements before posting, mostly cropping and making slight adjustments to lighting (shadows and brightness). I specifically bought the Pixel3a because of the high ratings for its camera plus its low cost relative to Samsung and Apple. It’s a few years old now, but I still love it.

      Liked by 1 person

  3. Great post. I loved seeing your photos of New England as autumn begins to set in. Going by what you show us you have moved into a very beautiful part of the US (although I would rather look at winter there through your lens than my own eyes).

    I’ve generally had bad experiences with woolly caterpillars; most cause itching and irritation. Interesting that this tiger moth caterpillar is covered with non-irritant setae.

    Liked by 1 person

    1. Thank you! Yes, I seem to have (luckily) landed in a truly beautiful place. I’ve been warned several times about the “harsh winters” here, but we had some pretty hard conditions in Idaho’s mountains, so I’m not deterred.

      You’re so right about most woolly caterpillars; not worth the risk of touching! Or most caterpillars, for that matter. I once had to drop out of an endurance triathlon in Canada because the bike ride, on a rainy day past some orchards, meant caterpillars on the pavement and flying off my front wheel into my eyes. Eventually my vision became so clouded I went to an ER eye doc that night to verify I wasn’t going blind! Thankfully temporary, and rare, but yeah, in general, best to stay away from caterpillars (except Woolly Bears)!

      Liked by 1 person

  4. Looks like you picked a lovely section of Vermont…. and definitely at the right time of year. Autumn is glorious. If you’re in the area I think you are, be sure to drive through the Notch to Jeffersonville before they close it in October. It’s a fun little drive.

    Liked by 1 person

  5. You sure landed in a beautiful place. That “old man’s pace” — that’s always been Bear’s pace. Thanks to her, I’ve learned to accept my pace and to see so much more than I did when I was running. It’s a trade-off, I guess. ❤

    Liked by 1 person

    1. I did – it’s so pretty here, reminding me of my early years in western Washington.

      Aging and a slower pace is a trade-off, for sure, but a worthy one. I hate to think of all I missed when I was always in such a rush.

      But I admit, I’m grateful that I get to enjoy both a walking and running pace, trading off days. Each has its rewards.

      Liked by 1 person

  6. As your neighbors have probably told you, the fall colors are late this year (because of all the rain this summer). I’m hoping for a cold winter. Last winter was mild. I like to cross-country ski in the cornfield behind the house, but the conditions were poor most of the winter (wet or icy). Maybe I live too far south. Maybe it’s time to head north with the Woolly Bears!

    Liked by 1 person

    1. No, I hadn’t heard that and didn’t realize the colors are late. It’s all new to me, no point of reference, but all good!

      I’m hoping for plenty of snow as well. If you don’t get enough “down south” then follow the Woolly Bears up this way, there are 300 acres open to me (and friends) for snowshoeing and xc skiing…!

      Liked by 1 person

  7. You got me to look up the subject of Woolly Bears on the Goog. The internet is such an informative place. As evidence, I present the following excerpt, taken directly from my front search page:

    Q: What does woolly bear poop look like?
    A: Woolly bear poop doesn’t stink. It looks exactly like peppercorns.

    Liked by 1 person

  8. It’s started already? I wont be there for 3 more weeks. I hope the colors last. Wow, really hard to find a hotel room in the fall. I love this time of year, the wooly bears are so on the move. Every run or bike ride I see plenty. Once on a long run I made up my own folklore rhyme about them. Then I tried to convince my kids it had been around for centuries. They’re too smart for me.

    Liked by 1 person

    1. Yes, the leaves seem to be ramping up, more color every day! I have a friend from WA visiting mid-October, so yeah, I hope they last as well.

      Maybe you could share your woolly bear rhyme on your site, an ode to autumn? Your kids’ reactions would make a fun read! “Oh, Dad…. As if.”

      Liked by 1 person

  9. Very interesting. I was a little worried when I saw the title and wondered where the heck did you move to?! Haha. I am glad all will be well with the woolly bears, assuming they find a spot to hide and winter it out. And omg, your photos are stunning. Loved the one with the reflection on the water.

    Liked by 1 person

  10. I had completely forgotten about woolly bears, but this jogged my memory! We have some species of caterpillar here also referred to sometimes as woolly bears (possibly the same ones, I’m not sure). At least, my mum called them woolly bears when I was little.

    Liked by 1 person

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