The National Weather Service uses sophisticated computers to predict how severe the Iowa winter ahead may be, but more down-to-earth forecasters are available — wooly bear caterpillars. Entomologist Phil Pellitteri has been studying the fuzzy insects for years and finds they’re fairly accurate.
Pellitteri says, “The ones that I have been seeing have had a relatively wide reddish band which is usually suggestive of a warm winter, so I am pleased at that.” So forget about the “El Nino” effect and the Old Farmers Almanac, head out into the woods and find the black-and-red bugs.
Pellitteri says you want to gauge the size of the red hairy band around the caterpillar’s mid-section versus the amount of black on the ends. More red, he says, means a warmer winter. “The tough thing is, it always depends on which critter you pick up,” Pellitteri says.
“It does vary. The ones from this year, it’s approaching 55-to-60-percent of the total body length, which is a good sign. If it’s relatively minimal, 20 or 30%, that’s not a good sign.” While the color of a caterpillar’s fur likely has nothing to do with Iowa getting a foot of snow or 20-below wind chills, he says it’s fun to think it might.
“It’s only pretty accurate because you tend to find people like you better when you say it’s going to be warm,” Pellitteri says. “To be honest, the science of it isn’t there. It’s done more tongue in cheek, but, using just what you see and predicting the warm side most of the time seems to be the way things have panned out.”
He says he’s been studying the caterpillars over the past three decades and their winter predictions have been correct about 70% of the time.