Identification guide to Nordic aphids associated with mosses, horsetails and ferns (Bryophyta, Equisetophyta, Polypodiophyta) (Insecta, Hemiptera, Aphidoidea)

Keys and diagnoses of North European aphids (Hemiptera, Aphidoidea) associated with mosses, horsetails and ferns are given, based on fresh and freeze-dried material. Numerous externally visible and thus informative characters, that are absent in cleared, slide-mounted specimens, such as body shape colours, wax coating and pattern etc., are utilized. Most of the species are illustrated by photographs of live specimens and drawings. Root-feeding species living in the moss layer or otherwise often present in moss samples are also included, even if their hosts were spermatophytes. The combination of colour images and diagnoses, utilizing easily observed characters, allows the identification of a large number of species already in the field, and many more at home with the aid of a stereo microscope. Host plant relationships and association with ants are summarised, including new records. Brief accounts on aphid life cycles, freeze-drying preparation techniques, etc. are also given to support the use of the keys.