What do woolly bears know about winter?

“Orange and black woolly caterpillar covered with fur a shady leaf beneath an oak choose any leaf you prefer wrap up in your cocoon and hide come out in spring as a beautiful butterfly” — Anonymous A couple of weeks ago, we and our hiking buddies did our last trek on the Ice Age Trail for this year. One of the things that distinguished this walk from others was the appearance of many woolly bear caterpillars on the road. I think a lot of people in Wisconsin have heard at one time or another that if you want a forecast for the upcoming winter, all you have to do is to just look for a woolly bear caterpillar (black at both ends and reddish-brown or rust-colored in the middle). In early October the woolly bears leave their food plants (they feed on a variety of grasses and weeds including plantain, dandelion and nettles) in search of a dark and sheltered spot where they can hibernate as larvae for the winter. If you pick them up, they curl into a tight little ball and “play dead.” Cute little creatures. But can they predict the weather? The woolly bear caterpillar has 13 segments to its body, which traditional forecasters say correspond to the 13 weeks of winter. According to folklore, the number of black segments on the woolly bear in autumn varies proportionately with the severity of the coming winter in the locality where the caterpillar is found. The more black bands, the longer, colder, snowier and more severe the winter will be. Similarly, the more brown bands in the middle, the milder the upcoming winter will be. Some people think that the position of the longer dark bands can indicate which part of winter will be coldest or hardest. If there are more black segments at the head end of the caterpillar, the beginning of winter will be severe. If the tail end has more black segments, the end of winter will be cold. In addition, as is true with most folklore, there are other versions to this legend. One says that the length of a woolly bear’s coat will indicate the upcoming winter’s severity. So, if its coat is very woolly, it will be a cold winter; if it’s a little sparse, the winter will be less severe. Another version deals with the woolly bear caterpillar’s direction of travel. If the woolly bears are crawling in a southerly direction, they are trying to escape the cold winter conditions of the north. On the other hand, if the caterpillar is crawling on a northward path, a milder winter is on the way. So OK, the ones we saw were almost all going across the road from west to east. What does that mean? And the black segments, front and back, were about the same length as the brown segment in the middle. Milder winter? I hope so. OK, now I’m going to get all scientific and debunk the myth based on some research I did on the always-reliable Internet. I found out that 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 anything! Sorry. The woolly bear caterpillar’s coloring is based on how long the caterpillar has been feeding, its age and species. (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 better the growing season is, the bigger the caterpillars 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. These little creatures shed their skins (or molt) six times before reaching adult size. With each successive molt, their colors change, becoming less black and more reddish. This results in narrower red-orange bands in its middle. So, the width of the banding front and back is an indicator of the current or past season’s growth rather than an indicator of the severity of the upcoming winter. So what do you think? Do you like the myth or the science? Do woolly bears predict winter weather?