It is recorded as a pest on apples and pears in Europe, but only when natural enemies are lacking. Heavy infestations of ash whitefly can also produce large amounts of honeydew which in turn promotes the growth of sooty mould. Ash whitefly is highly polyphagous and can be found on many small trees and shrubs. It is common for polyphagous whiteflies to broaden greatly host range during outbreaks. Life cycle Ash whitefly reproduces quickly in summer and may pass through approximately three generations.
Adults lay eggs on the underside of most leaves, so the whole canopy can be infested.
The first instar is the only mobile juvenile stage, but even this stage rarely moves more than a centimetre. After settling, the insect remains in the same position until it becomes an adult .The nymphs and adults feed on sap. The 'pupal' stage is the resting stage from which the adult emerges. There are many overlapping generations in a year, and at any time all stages may be present on leaves. The preferred hosts in spring, summer and autumn are the deciduous ash, pomegranate, pear and apple.