Progeny of individual females of Lecanium spp. from orchard, ornamental, and wild trees and shrubs were colonized on rooted willow cuttings in a greenhouse and insectary. Some forms with distinctive morphological and colour characters on their original hosts maintained these characters through one to six generations on willow. These results and many years’ observations indicated that lecanium scale infestations in fruit orchards of the Niagara Peninsula, Ontario, were usually composed of a complex of forms. Some of these were distinct species but others, less sharply differentiated, were considered as varieties of these species. One new species is described.