For many years there has been considerable confusion between the names Psylla Geoffroy, 1762, Chermes Linnaeus, 1758, and Adelges Vallot, 1836. Family names have been derived from all three generic names and Chermes itself has been used in five different ways in four different famihes of Homoptera. In the foUomng account the anglicised word " psjdlids " is used for the jumping plant lice knowii as Psyllidae (or sometimes Chermidae) ; '■ adelgids " for the family of Aphidoidea known as

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... (or sometimes Chermidae) ; " aphids " for Aphididae in a broad enough sense to include Eriosoma but to exclude Phylloxeridae and Adelgidae ; and " coccids " for Coccoidea. The name Chermes has been used both for Coccoidea and Aphididae in addition to its better known uses for Adelgidae and PsylUdae. 2. Linnaeus (1758, Syst. Nat. (ed. 10) 1 : 453-455) proposed the name Chermes for fourteen species, nine of which are currently accepted as psyllids, one as an aphid and one as an adelgid. The other three have been referred to as psyllids by some authors but this has been disputed by others so that the names are usually now regarded as nomina dubia. The three species included by Linnaeus and subsequently selected as types of the genus are the psylUds Chermes alni (: 454) and Chermes ficus (: 455), now usually called Psylla alni (L.) and Homotoma ficus (L.) respectively, and the adelgid Chermes abietis now View This Item Online: https://www.biodiversitylibrary.org/item/44462