The Macrosiphini are the predominant group of aphids on herbaceous plants in Britain, and the world. There are 305 British species and subspecies, comprising 49% of the 620 Aphididae on the British list. They include many important pest species, some of which are highly polyphagous, but there are also very many more species feeding more-or-less specifically on indigenous and naturalised plants and playing a significant role in natural food chains. This Handbook provides a checklist and a list of native host plants, along with keys to tribes, genera and species. Biological information is provided about each species.