What makes woolly worms so unique

Thousands of visitors will make their way to Banner Elk on Saturday, Oct. 16 and Sunday, Oct. 17 for the 44th annual Woolly Worm Festival 

They’ll watch the woolly worms race and see the fuzzy black and brown creatures on all manner of merchandise and signage on the festival grounds. The fanfare for the little critters begs the question, what are woolly worms and why have they become such celebrities? 


Origins of the Woolly Worm Festival  

In the 1970s, Mountain Living Magazine editor Jim Morton was preparing a woolly worm forecast for the winter issue of the magazine. After photographing a woolly worm for the story, he noticed a second woolly worm that looked completely different.  

Morton immediately knew he needed to find some way to determine which worm would forecast. The tradition evolved into the annual “crowning” of a woolly worm to be the official predictor of the severity of winter during a festival in October. The worm earns the forecasting rights by winning a series of races. 

Woolly worms have 13 segments, which are said to correspond to the 13 weeks of winter. Light brown segments predict a mild week of winter and dark black segments mean cold, snowy periods. 

Whichever worm emerges as race champion has its colors closely examined, with the region’s winter weather forecast hanging in the balance. Longtime festival fans say the woolly worm has about an 80–85 percent accuracy rate with its annual predictions.  


What is the woolly worm? 

The woolly worm is the caterpillar stage of the Isabella Tiger Moth. Adults fly during much of the summer, then mate, and lay eggs. The caterpillars seen roaming in abundance during October are the result of that process.  

Adult moths only live for a few days and don’t eat. The entire life cycle from egg to adult can be completed in just a few weeks, said Cody Porter, assistant professor of Wildlife Biology 

Unlike adult moths, caterpillars eat plenty and enjoy the leaves of at least 39 different species of plants, including black cherries, maples, birches, and asters.  

“The caterpillars are extremely generalized feeders, meaning they eat a wide range of plants,” Porter said. “At this time of year, when they are active and moving around, they are seeking sheltered places to go dormant for the winter.” 

Ideal shelter spots for woolly worms include under or inside logs, under large rocks, or other dark, safe areas that offer shelter from the elements.  


What makes them unique 

Porter said many caterpillars have setae, or bristles, like the woolly worm. Most caterpillars don’t get around quite like the woolly worm. 

“I think what makes this species unique is that it is extremely mobile and abundant,” Porter said. “At this time of year, on warm days especially, they can be seen scurrying across the roads and sidewalks at a pretty impressive pace for a caterpillar.” 

Porter added that woolly worms have color variance. Some have almost no black, while others are almost entirely black. That unique coloration is often short-lived. 

“The Isabella Tiger Moth is probably never or only very rarely entirely black,” Porter said. “There are different species of moths whose caterpillars are all black, such as the Giant Leopard Moth.” 


Why all of the hype? 

Porter said he thinks woolly worms have caught on as an official mascot of winter weather predictions primarily because of their abundance and mobility.  

“Because they are most active just before colder weather sets in, and they are so variable in coloration, I think it’s easy to imagine how a folklore has developed around them and their predictive power over the coming winter,” he said.  

Banner Elk’s Woolly Worm Festival isn’t the only one of its kind. Porter said he knows of at least five other similar festivals in the Eastern United States. One similar festival, dubbed The Woollybear Festival, happens each fall in Vermillion, Ohio.  


The local impact  

The woolly worm might be tiny, but the popularity of the festival is not.  

The Woolly Worm Festival brings 15,000 to 20,000 visitors to the area. Past festivals have attracted as many as 170 vendors and 1,000 woolly worm race entrants.  

The event has appeared in the Farmer’s Almanac and Kiwanis International Magazine. Festival proceeds benefit community efforts and charities.  

Learn more about the Wildlife Biology program.

By Cory SpiersOctober 15, 2021
Campus LifeCommunity