Woolly worms, also known as woolly bear caterpillars, turn into Isabella tiger moths (Pyrrharctia Isabella) in the spring. They spend the winter as caterpillars, sheltered from the weather under tree bark or debris, or in garages, and hibernate by creating a natural organic antifreeze called glycerol. When daytime temperatures reach around 50 degrees in the spring, the woolly bear caterpillar becomes active again and feasts on springtime greens such as dandelions, replenishing its energy before it transforms into a moth. Woolly worms have a reputation for being able to forecast the coming winter weather, with some people believing that the thickness of their hair or the direction they are traveling can indicate the severity of the winter ahead. However, there is no scientific evidence to support this belief.