This chapter highlights some of the problems of interpreting the observed variation within and between aphid species, and discusses what the names given to aphids really mean. Fourteen taxa that probably head the list of economically important aphid species are discussed as examples (Acyrthosiphon pisum, Aphis craccivora, Aphis fabae, Aphis gossypii, Aphis spiraecola, Diuraphis noxia, Lipaphis pseudobrassicae [Lipaphis erysimi], Macrosiphum euphorbiae, Myzus persicae, Rhopalosiphum maidis, Rhopalosiphum padi, Schizaphis graminum, Sitobion avenae and Therioaphis trifolii).

This chapter looks at aphids from a taxonomist's viewpoint. It highlights some of the problems of interpreting the observed variation within and between species, and discusses what the names given to aphids really mean. Then, as examples, it discusses 15 taxa that probably head the list of economically important aphid species: Acyrthosiphon pisum, Aphis craccivora, A. fabae, A. gossypii, A. spiraecola, Diuraphis noxia, Lipaphis pseudobrassicae [L. erysimi], Macrosiphum euphorbiae, Metopolophium dirhodum, Myzus persicae, Rhopalosiphum maidis, R. padi, Schizaphis graminum, Sitobion avenae and Therioaphis trifolii. Developments in image analysis now make the acquisition of morphometric data far quicker and easier, and it is hoped that future work on aphid species complexes using molecular methods will always aim to include parallel morphological studies.