This book presents a monograph of all species of the genus Dyscia Huebner, [1825] (Lepidoptera, Geometridae: Ennominae). Nineteen species are recognized for the Palearctic region, previous records from other regions are wrongly attributed to the genus or mislabelled. The work comprises descriptions of adult morphology, based on external features and genital characters. Autapomorphies of species taxa are outlined. Previous knowledge on bionomics and distribution is summarized, information on immature stages is supplied for several species. Distribution maps are presented with references to all localities for all species. Habitus and genitalia are illustrated for both sexes of all species, except for Dyscia rungsi and Dyscia dodonaeeti, of which only males were available to us. Photos of the larvae of eleven species, and habitats of fourteen species are given. Keys using genital characters and external features will facilitate identification of males and females.