Can Woolly Bear Caterpillars Really Predict Snow?

If you live in the Hudson Valley you probably have heard that a certain caterpillar can predict how much snow we'll get during the winter.

The Woolly Bear Caterpillar makes its appearance in late summer and early fall. Sometimes called the Woolly Worm or Fuzzy Bear, these quiet little creatures have a reputation for being excellent meteorologists.

As legend has it, Hudson Valley residents can tell just how much snow we'll get over the winter by the amount of black on the caterpillar's body. The Wooly Bear has two black bands on their head and tail end and one brown band in its middle. Supposedly, if there is more black on the head, we'll have lots of early snow. If the back end has a larger black band then we'll see more snow later in the season. In fact, some even believe that the caterpillar's 13 segments correspond with the 13 weeks of winter, and carefully inspecting the insect will tell you exactly which weeks we can expect to see snow.

It all sounds like it makes sense, right? Well, according to the National Weather Service, predicting the weather by looking at a bug is just crazy.

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.

 

In fact, it turns out that the bands also indicate just how old the caterpillar is. These woolly creatures shed their skin many times before becoming an adult. As they shed, their colors become less black. So if you see an all-brown Woolly Bear he's actually just an adult, not a predictor of a mild winter.

So, if you see a Woolly Bear Caterpillar crawling around your yard, don't take it as a sign of things to come. For that, we should probably just stick to more scientific methods, like counting the amount of acorns that have fallen on your sidewalk.