By Staff
In the hallowed annals of folklore, two animals reign supreme as weather forecasters. The groundhog is in charge of spring's arrival while the woolly bear caterpillar alerts us to the upcoming winter's severity. As you know, the woolly bear caterpillar has three distinct color bands roughly the same width, black at head and tail and rust colored in the middle. We've all heard the tale. If the black bands are unusually long the coming winter is destined to be severe. If the rust colored middle band is dominant the winter will be mild.
That's just the amateur version of the folklore, though. Some say the length and density of the stiff, bristly hairs must also be considered, the longer and thicker the coat the more severe the winter. Other versions go deeper yet.
The woolly bear has 13 segments and as legend goes these correspond to the thirteen weeks of winter. A given segment(s) with exceptionally long dark hairs means that corresponding week(s) of winter will be severe and vice versa. It's also said if the caterpillar is traveling south it's fleeing a cold winter. If traveling north the winter will be inconsequential. For some reason legend ignores other points of the compass.
Before we get into the scientific aspects of this we should know the woolly bear caterpillar is the larvae stage of the Isabella tiger moth.
This is a common moth throughout most of North America. It's a rather unremarkable orange and cream color with a wingspan of one and a half to two inches. Like most moths it is nocturnal. Starting about now woolly bear caterpillars are on the move looking for a dark, secluded spot to hibernate such as underneath bark, a stone or fallen log. Amazingly, during hibernation they create a natural, organic antifreeze.
The caterpillar freezes bit by bit until everything but the interior of each cell is frozen. They can withstand temperatures up to 90 below and can survive all winter frozen in an ice cube.
So what better place to turn to check out the veracity of this winter forecasting phenom but the National Oceanic and Atmospheric Administration, the world's leading weather agency.
As one would expect, for the sake of job security NOAA's scientists are duty bound to debunk their competition. According to them the color, length and density of hairs are simply factors of how long and well the caterpillar has been feeding and its age. The better the growing conditions the bigger and woollier the caterpillar will be and the smaller the middle rust band. Also, the caterpillar molts six times on its way to maturity. With each successive molt it becomes less black and more brown.
To further complicate things there are some 260 species of tiger moths in North America and many of their caterpillars resemble the Isabella tiger moth's woolly bear but with varying amounts of black and brown. As for direction of travel, well, even I'll admit that a Michigan caterpillar ain't about to migrate to Florida.
That's NOAA's spin. Now let's look at the rest of the story. The woolly bear goes back centuries in folklore but it was Dr. Curran of the Museum of Natural History in New York that brought it to the forefront in 1948 with a marginally scientific but highly publicized study of band measuring and weather comparison. He touted 100 percent accuracy because over an eight year period the middle bands were wide and the winters were mild.
Okay Doc, sounds 100 percent conclusive to me. In 1988 some school kids and others in the region resumed his cutting edge work which continues today. They claim 80 percent accuracy. Then there's the ex-mayor of Banner Elk, North Carolina, one of several towns holding an annual woolly bear caterpillar festival, who has for years observed the correlation between caterpillar body segments and the weeks of winter. He claims 70 percent accuracy.
How dare NOAA try to contradict such overwhelming evidence as all that? The next thing we know they'll be trying to discredit Punxsutawney Phil, the world's foremost spring forecasting groundhog with a documented accuracy of 20 percent. Carpe diem.