Aphids on the World's Plants - Blackman & Eastop's seminal works, in digital form
Aphid identification and information at Influential Points, with a focus on the European fauna
Wikipedia - All about aphids
Aphid Species File - Taxonomic, nomenclatural, and bibliographic database
Fauna Europeae - Aphidoidea
Tree of Life - Aphidomorpha
Andy Jensen's photostream - An aphid taxonomist's photos of live aphids
Biodiversidad Virtual - Aphidoidea of Iberia
BioLib - Biological Library, Aphidoidea
Bug Guide - North American aphids
Bugwood: insectimages.org Family Aphididae
Plant-Diseases.com - Selection of European pest aphids
AphidBase - Aphid genome database
Pea aphid Expressed Sequence Tag database
Barcode of Life BOLD Systems - Aphididae, Adelgidae, Phylloxeridae
9th International Symposium on Aphids - Beijing, China, 2013
Mohsen Mehrparvar's Aphidology.
Mauro Mondrioli's blog, The Aphid Room.
Gexia Qiao's Lab of Systematics and Evolution of Aphids.
Petr StarĂ½'s Laboratory of Aphidology.
Alex Wilson's Lab.
Aphids on the World's Plants - Blackman & Eastop's seminal works, in digital form
AphID - An identification key to the world's most polyphagous and/or cosmopolitan aphids
Aphid identification and information at Influential Points, with a focus on the European fauna
Aphids of Quebec - Species list, photographs, predators, parasites, references (in French)
Aphis of the midwestern USA - 3I interactive key