The genus Lymantria Hübner [1819] contains some of the most destructive forest pests in the world. Potential invasive species of Lymantria from temperate and sub-tropical Asia are a threat to the forests of North America. Treated here are 31 species and two subspecies of Lymantria that if accidentally introduced into North America could result in severe economic loss to native forests. Three species are described as new Lymantria (Porthetria) brunneoloma, n. sp. from China, Lymantria (Lymantria) pulverea, n. sp. from Taiwan, and Lymantria (Nyctria) flavida, n. sp. from Japan. Lymantria (Porthetria) dispar asiatica Vnukovskij, revised synonymy is a synonym of Lymantria (Porthetria) dispar japonica (Motschulsky). Lymantria (Porthetria) umbrosa (Butler), revised status is considered a valid species and a lectotype was designated to establish nomenclatural stability. Lymantria (Porthetria) albescens Hori and Umeno and Lymantria (Porthetria) postalba Inoue, revised status are considered valid species. Descriptions, distributions, and illustrations of adults are included. Larvae of thirteen species and two subspecies are described and illustrated. Sections provide information on oviposition, biology and behavior, food plants, pheromonal communication, flight and pheromone periodicity, and seasonality when known. Analysis of the Lymantria dispar species complex and Lymantria mathura using mitochondrial gene COI resulted in taxonomic changes.