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The Emergence of the Wolly Bear Caterpillar and Its Connection to the Fall


OHIO – If you have been on social media you may have seen people posting photos of this brown and black caterpillar called the Wolly Bear and heard the superstition of its ability to detect the severity of our winter.

The Wolly Bear shows its fun color in the fall in one if its life stages, this moth larvae form is heavily covered in brown and black fur. The caterpillar emerges in the fall from an egg and over the winter spends its life as the furry little caterpillar you see now. The small creature survives winter freezes by producing a cryoprotectant in its tissues. Once the weather warms, the larva devours all the grass and weeds it can, pupates, and becomes an adult Isabella tiger moth.

The fuzziness serves a purpose also it’s not there to keep the caterpillar warm but actually control its ability to freeze controllably. This is extremely helpful for this insect in the northern areas of the world where they are as common as they are here.

Some people believe common folklore, which has it that the forthcoming severity of a winter can be predicted by the amount of black on the caterpillar, but sadly that’s not true a statement from the National Weather Service

“The woolly bear caterpillar’s coloring is based on how long 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.”

The caterpillar may be found this winter underbrush or an object that hasn’t moved since fall. It will seem that the caterpillar may be dead, but shhhh he’s just sleeping.