The Saturniidae are members of the Superfamily Bombycoidea. These species are medium to very large in size, and this family includes the largest moths in North America. Adults have a wingspan of 3 to 15 centimeters, relatively small heads, and densely hairy bodies. Larvae are usually very fleshy, with clumps of raised bristles. Buck moth and Io moth caterpillars have sharp, stinging hairs. Caterpillars mostly feed on leaves of trees and shrubs; some cause severe damage. Pupa develop in silken cocoons or in the soil. This family does not contain the commercial silkworm moth (Bombyx mori), which is not native to North America.