A Technical Report from The Bartlett Tree Research Laboratories
Small sap feeding insects, generally 1-5mm long with soft bodies. More than 500 species occur in Britain and northern Europe. Those that attack trees include, green apple aphid, large willow aphid, pear-bedstraw aphid, damson hop aphid, cherry blackfly, elder aphid, lime leaf aphid, sycamore aphid, and beech aphid. Aphid body colour varies between species i.e. green apple aphid, which infests ornamental apples, pears, rowan and hawthorn is a bright to yellow green colour, while large willow aphid, is dark brown covered with fine grey hairs. Young, vigorous trees, or those heavily fertilised with nitrogen, are most severely affected.