630 UK species. Commonly referred to as greenfly or blackfly (although they can be of varying colours), aphids belong to the superfamily Aphidoidea. There are around 5,000 species worldwide. These small insects are well known for their pest status as sap suckers to gardeners and growers alike. They can be quite significant pests in horticulure and agriculture. Many species are host specific, whilst other are polyphagous, feeding on a variety of hosts. Many species of aphid reproduce parthenogenetically during the main feeding season and are also viviparous, giving birth to live young. Many species of aphid have close associations with ants, which feed on the sugary ‘honeydew’ excreted from the anus of the aphids. In return the ants help to protect the aphids from predators, and they may also move them to suitable locations to ‘farm’ them. Aphids provide an important food crop for many insects and other arthropods. Ladybirds, lacewings, parasitic wasps, other true bugs, and some species of hoverfly larvae rely on aphids to survive.

Macrosiphum (Macrosiphum) rosae

Myzus (Nectarosiphon) persicae

Aphis (Aphis) farinosa

Periphyllus testudinaceus

Aulacorthum (Aulacorthum) solani

Pemphigus spyrothecae
I am extremely grateful to the entomologist Alice Casiraghi from the University of Barcelona, for helping me to accurately identify these species. Without her expert help this page would not exist, so I dedicate this to her. The excellent facebook page called The Aphidologist is dedicated to the world of aphids.
Other sites of interest:
InfluentialPoints.COM
Aphids On The World’s Plants
NBN Atlas
iRecord