In addition to three pairs of legs on the thorax, they have two to eight pairs of fleshy abdominal prolegs that are structurally different from the thoracic legs. It uncoils by hydrostatic pressure and acts as a siphon tube for sipping liquid nutrients, such as nectar, from flowers and other substrates. At rest, their wings are held horizontally against the substrate, folded flat over the back, or curled around the body.
Some species are extinct or nearing extinction, others are very common.
The silverspotted skipper, Epargyreus clarus , is a common species. According to folklore, larvae of the banded woollybear, Pyrrharctia isabella , can forecast the severity of winter weather. A wide brown band means the winter will be harsh, a narrow brown band means the winter will be mild. Some species of Arctiidae even produce high-pitched ticks that confuse the bats.