Woolly apple aphid

The woolly apple aphid is an approximately 2 mm large aphid that lives on plant sap sucked from young twigs and pruning wounds.

Also known as:
Woolly aphid
American blight

recognize fungus caused by the woolly aplle aphid
Fungus caused by the woolly apple aphid on apple tree (James Grieve), photo: Lieve Govaerts

Woolly apple aphid (Eriosoma lanigerum) is native to North America. The approximately 2 mm large aphid derives its name from the red spots that appear when the aphid is crushed. The red-brown woolly apple aphid belongs to the aphids and lives on plant sap sucked from young twigs and pruning wounds. The leaves leave this aphid undisturbed. The aphids leave white sticky fluff on the branches.
Galls and woody outgrowths develop on the spots punctured by the aphids. Larvae of the woolly apple aphid overwinter both above ground and underground on the roots and cause damage: stunted growth occurs and the tree dies if it is heavily infested.
Apple aphids can spread fungi such as Neonectria ditissima. This fungus appears on the wounds caused by the breakdown of the galls and is the cause of apple canker.
Ladybugs, earwigs, lacewings and the larvae of parasitic wasps are the natural enemies of the woolly apple aphid.

Affected plants

Control

Usually no control is necessary: the natural enemies keep a possible population limited.
In case of an infestation of woolly apple aphids, control the aphids with natural pyrethrum, spirit soap, soap suds, rhubarb solution or nettle solution.

Prevention

Earwigs, parasitic wasps and gall midges are the natural enemies of the woolly apple aphid, the aphid that spreads fungus. So do not destroy these insects.