The taxonomy and biology of the ennomine genus Mnesampela Guest is reviewed. Several species are well known in southern Australia as defoliators of gumtrees (Eucalyptus spp.) in cultivation. Seven species are recorded in the genus: privata (Guenée) (= inordinata Walker), comarcha Guest ( = comarcha Meyrick), lenaea Meyrick, heliochrysa (Lower), and three new species: athertonensis from the Atherton Tableland of north-eastern Quccnsland, kunama from high altitudes in south-eastern mainland Australia, and arida from the subinterior of southern Australia. A key to the species is provided and all species and their genitalia are descrihed and illustrated. Details of the immature stages, foodplants, flight periods, and distribution of the various species are also recorded. One new synonymy is established and two lectotypes are designated.