Ash Whitefly - Siphoninus phillyreae (Haliday) (Aleyrodidae: Hemiptera)
Prof Jan Giliomee noticed Whitefly for the first time in SA, followed by Ian Miller (taxonomist). This is yet another Whitefly to enter SA, after the discovery of Woolly Whitefly (Aleurothixus floccosus), which attacks citrus, by Prof Giliomee.
These insects are not actually flies, but are more closely related to aphids and scale insects.
How to indentify whitefly:
All whiteflies are best identified by their pupae, small immobile structures 1.5 mm long, usually clustered on the underside of the leaves of its host. Ash Whitefly pupae characteristically appear to have greyish bands on a pale/whitish body. Adult Ash Whitefly have slightly mottled wings but otherwise are a pale whitish whitefly indistinguishable from many other different species.
Which plants are hosts:
In order of preference (i.e. plants most likely to be attacked):
Members of the Oleaceae, including many species of Fraxinus (e.g. Claret ash, Golden ash etc), Olea (Olives) and Phillyrea.
Members of the Rosaceae including many species of Crataegus, Malus, Prunus, Pyrus (eg Hawthorn, Apple, Plum, Pear)
Puniaceae: Punica granatum (Pomegranate)
A variety of other plants, including various species of citrus, magnolia, and crepe myrtle, are likely to be occasional hosts for this pest.
The life cycle:
Development only occurs between temps of 10° and 30°C with optimal temps between 20-25°C. Winged adults lay eggs on underside of leaves. Nymphs emerge, rarely moving more than one centimeter. The nymphs feed on tree sap until pupation. Pupation occurs in situ with larvae on undersides of leaves.
Contact: 083 267 96 39
Willem Avenant - Tree Specialist - Western Cape, Cape Town
Peter S Gillespie