Keys and descriptions of some of the aphids belonging to the Macrosiphini occurring in Scandinavia are given with drawings and colour plates. Among the genera are Myzus, Nasonovia, Acyrthosiphon and Macrosiphum. The other genera and species of Macrosiphini are treated in vol. IV and the coming vol. VI, which is the last one of The Aphidoidea of Fennoscandia and Denmark. Descriptions include morphology, distribution and biology.