They are members of the Ermine moth family. Once a female lays her eggs in her old cocoon (for protection), she dies. Only one generation of moths lives every year. The eggs overwinter in their case and emerge as caterpillars in the spring. Larvae create and share a web on leaves and branches of the Ailanthus tree, also called Tree of Heaven. Though the moth is named after one type of tree, a variety of plants and shrubs are food for the caterpillar. Other host trees come from the Simarouba genus. The webs these caterpillars make are unattractive to some and therefore this species can be a pest, especially in plant nurseries.
Adults are active in the daytime and can be seen from spring through autumn. They are considered good pollinators.