Wingless females have a pear-shaped bright green or yellowish-green body, undusted with wax particles, and grow to a maximum length of about 2.2 mm (0.09 in).

[3] Besides occurring on apple (Malus domestica), Aphis pomi infests other plants in the family Rosaceae including pear (Pyrus communis ), hawthorn (Crataegus monogyna), medlar (Mespilus germanica), quince (Cydonia oblonga), mountain ash (Sorbus aucuparia), rose (Rosa) and spiraea (Spiraea).

[1] Overwintering eggs hatch in spring and the aphids colonise the growing tips of the shoots causing the edges of the leaves to curl.

In June some winged females are produced and these migrate to other branches and trees, and large aggregations build up by late summer.

[2] High levels of infestation by the aphids can cause stunted shoots, disfigured fruit and premature leaf fall, especially in young trees, and sooty mould may form on excess honeydew secretions.