On the life cycle of Pemphigus (Pemphiginus) populi Courchet with a key to British species of Pemphigus Hartig (Hornoptera: Aphidoidea)

Experimental and field observations are given on the biology of Pemphigus (Pemphiginus) populi Courchet with a description of the secondary host morphs from the roots of Melilotus altissima, Lathyrus pratensis and Medicago lupulina. Twelve species of Pemphigus Hartig are recorded for Britain in three subgenera: Pemphigus with nine species, borealis Tullgren, bursarius L., filaginis (B. de F.), gairi Stroyan, phenax Borner and Blunck, pvotospirae Licht., rubiradicis Theob., saliciradicis (Borner) and spirothecae Pass.; Parathecabius with two species, lysimachiae (Borner) and auriculae (Murray); Pemphiginus with one species populi Courchet. A key to the alate migrants, alate sexuparae and apterous alienicolae is given with notes on the biology of all the species except borealis and rubiradicis.