Tent caterpillars are moderately sized species in the genus Malacosoma in the moth family Lasiocampidae. Species occur in North America, Mexico, and Eurasia. Twenty-six species have been described, six of which occur in North America. Some species are considered to have subspecies as well. Although most people consider tent caterpillars only as pests due to their habit of defoliating trees, they are among the most social of all caterpillars and exhibit many noteworthy behaviors.