Whitefly are small, sap-sucking insects that attack a wide range of greenhouse and indoor plants, brassicas (broccoli, Brussels sprouts, cabbages, calabrese, cauliflowers and kale), Viburnum tinus and the strawberry tree Arbutus.
They have a yellow body and white wings and measure 1-2mm (1/16in) long.
Whitefly breed very quickly in summer and produce such large numbers, that clouds of them erupt and fly off the plant when disturbed or the plant is brushed past or moved.
The adult whitefly lay pale yellow or grey eggs either individually or in circles on the undersides of leaves. These hatch into tiny larvae, which look like pale yellow or translucent, flat, scales that can move around at first and then become immobile.
There are three main types of whitefly. The commonest are greenhouse whitefly (Trialeurodes vaporariorum), cabbage whitefly (Aleyrodes proletella) and viburnum whitefly (Aleurotuba jelinekii).