Commonly called a "woolly bear," this larva of Pyrrharctia isabella is a species of moth (known as the Isabella Tiger Moth) with a wide distribution across North America. As the weather gets cooler this caterpillar will go dormant for the winter beneath leaf litter and loose tree bark. During dormancy, when temperatures drop, this species produces a cryoprotectant that insulates their tissues to prevent ice from forming in the hemolymph (circulatory fluid). A combination of dehydration and cold acclimation drive the synthesis of the cryoprotectant compounds.
I'm usually hesitant to pick up fuzzy caterpillars if I don't know what they are. My cousin, Sarah, has more experience with these and picked it up right away. Sometimes the setae (the little fuzzy spines) of caterpillars can irritate the skin or even cause severe pain in some instances. This species, however, is perfectly safe to handle.
As you can see in the photo, the caterpillar has curled up. They will respond this way to a disturbance, staying still in order to appear dead.
The woolly bear caterpillar draws a huge crowd in Vermilion, Ohio every year. According to The Vermilion Chamber of Commerce, it is the biggest one-day festival in Ohio. For 41 years this fall festival and parade has brought people together to celebrate the caterpillar and its role in predicting the weather. Much like Punxsutawney Phil, the famed Groundhog who predicts the end of winter, the woolly bear is said to predict the winter weather based on the size of its orange-colored band in the middle of its body. However, like the lore of Punxsutawney Phil, this is not an accurate way to get a weather forecast. The size of the band is actually determined by the developmental stage, or instar, that the larva is in.
More reading and references:
Encyclopedia of Life: http://eol.org/pages/863046/details
Discover Life ID Guide: http://www.discoverlife.org/mp/20q?guide=Caterpillars
Triggering of cryoprotectant synthesis in the woolly bear caterpillar (Pyrrharctia isabella Lepidoptera: Arctiidae). Jack R. Layne Jr., Diane K. Kuharsky: http://tinyurl.com/lk3lug5
Stinging Caterpillars: A Guide to Recognition of Species Found on Alabama Trees. L. L. Hyche: http://www.ag.auburn.edu/enpl/bulletins/caterpillar/caterpillar.htm
Woolly Bear Festival: http://tinyurl.com/n6dcdvz and http://vermilionchamber.net/festivals/woolybear/
