Woolly bear caterpillars are partial to clover and violets, but like other caterpillars, they start out eating the plant on which their egg has been laid. These plants include trees such as maple and birch. The caterpillars also eat grass, nettles, dandelions and herbs.
Woolly bear caterpillars also eat burdock, different types of docks, nettles and lambs quarters. They also have been known to eat garden plants such as cabbage, spinach and other cole vegetables. Woolly bears also eat the leaves of corn and other grains. They are not often found on fruit trees.
Woolly bears sometimes eat plants that are full of alkaloids or tannins. These chemicals give the animal some protection against parasites.
Folk legend claims that a person can tell how hard a winter is likely to be from counting the bands on a woolly bear caterpillar. These bands are brown or orange in the middle of the animal's body and black on the edges. How many black bands the caterpillar has depends largely on how many times it has molted. The more times the woolly bear molts, the fewer black bands it has.
The woolly bear is the caterpillar of the Isabella tiger moth. Ironically, though the caterpillar is a voracious feeder, the moth doesn't eat at all.