Adult flannel moths are stout-bodied, and very hairy. Females have thin antennae while males' are feather-like. Larvae are called puss caterpillars and, with their long hairs, resemble cotton balls. They have venomous spines that can cause a painful sting and inflammation lasting for several days. In some cases, the sting may cause headache, nausea, and shock-like symptoms. Perhaps the most notorious for stinging is the caterpillar of Megalopyge opercularis. Caterpillars have 7 pairs of prolegs, while other Lepidopterae have 5 or fewer pairs. They feed on a wide variety of deciduous trees and shrubs.
