Many 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.