The adult female and all wingless nymphal stages of the maple mealybug, Phenacoccus aceris (Signoret), are redescribed and illustrated. The second-instar nymphs of both males and females produce a felt-like cover, which is secreted by numerous dorsal tubular ducts. A key is also provided to separate wingless immature stages of Ph. aceris, based on morphological features. The life cycle and biology of the mealybug on three different plant hosts, i.e., Acer negundo L., A. pseudoplatanus L. (Aceraceae) and Fraxinus excelsior L. (Oleaceae) over two years is presented and compared. Ph. aceris displayed similar developmental rates on all three host plants. Ph. aceris has one generation per year in Ankara, Turkey, and overwinters as third-instar females and male prepupae and pupae in hidden places on the trunk and branches of its host plants. The longest nymphal stage on all host plant species was the third-instar female and the male prepupa and pupa stage. In both sexes there were differences in the periods of occurrence of each developmental stage amongst years that may relate to variation in field temperatures.