The nymphs are salmon pink in colour with dark eyes and circular cornicles which are slightly raised from the surface of the abdomen.

[6][7] The hibernating nymphs are very dark green, almost black, although they may be paler and can be dingy yellowish-brown and lack the secreted white waxy covering.

[4] Each aphid may give birth to up to five live young a day allowing the rapid growth of colonies, with a total of over 100 nymphs in its life.

[4] The aphids feed on sap by piercing the outer integument of the host where it is thinnest and excrete a substance known as honeydew which contains a high proportion of sugars.

[8] The galls are more sensitive to cold weather than the surrounding tissue and burst at -18 °C(0 °F), the resulting damage providing the fungus with an entry site for reinfection.

Sometimes it is possible to see a circular hole on the upper surface of the aphid which the adult wasp created when it emerged from the body of its host.

[6] As well as the parasitoid, Alphelinus mali, these aphids are preyed on by the bug Anthocoris nemoralis, ladybirds, hoverfly larvae and lacewings.

The presence of earwigs Forficula auricularia on the trees can reduce the levels of aphid infestation, so encouraging these insects by providing shelters may be another means of biological control.

[1] Exclsuion experiments in Poland showed that the earwigs, and to a lesser extent the seven-spot ladybird Coccinella septempunctata were important in controlling the numbers of aphids later in the season while in the early Spring the pine ladybird Exochomus quadripustulatus was the main predator on the aphids.

[7] It has also been known to attack Japanese quince Chaenomeles sp..[8] There is some debate about the host plant of E. lanigerum as the wooly aphids collected from Ulmus americana are now considered to be a separate species, Eriosoma herioti which migrates from Ulmus americana onto similar species of plant which E. lanigerum has been recorded on.