Robust, medium-sized to very large (25–120 mm wingspan) moths, often drably colored and with reduced or simplified wing patterns. Males generally have conspicuously plumose antennae. Larval hosts are primarily trees and shrubs. Th e most familiar and biologically best-known North American lasiocampids are undoubtedly the tent caterpillars (Malacosoma spp.), as a result of the huge numbers of caterpillars present during periodic outbreaks. Th e vast body of literature on Malacosoma ecology and biology is testament to this; for an excellent introduction to tent caterpillar ecology see Fitzgerald (1995).

The family Lasiocampidae includes about 1500 species distributed worldwide (Lemaire and Minet 1999), with about 30 species in North America and five reported from AB. Th ey are most diverse in the tropics. Franclemont (1973) provided a diagnosis of the North American species. Th e taxonomy of the New World Malacosoma was revised by Stehr and Cook (1968). Despite their notoriety, a number of significant taxonomic uncertainties remain among the western taxa, and there is perhaps no better place than AB to investigate this; for example, see the notes on Malacosoma californica.