whitefly

Tiny four-winged insect related to aphids and scale insects. The adults barely exceed a length of 3 mm/0.12 in; their wings are dusted with a powdery white wax which they secrete. In temperate countries they may be found in glasshouses, where they are pests of plants, such as cucumber and tomato. They are widely distributed in the tropics, where they attack citrus trees. They injure the plant by feeding on the sap and excreting honeydew, which encourages sooty black mould to grow.

Classification Whiteflies are in family Aleyrodidae, order Hemiptera, class Insecta, phylum Arthropoda.

Development In general the eggs are laid on the undersurface of leaves in a characteristic circular or arch-shape, and are attached to the leaves by means of a stalk. Each female lays about 100 eggs that hatch into first-instar larvae, which are oval-shaped, have antennae, walking legs, and feed actively by means of their stylets and proboscis. The mobile first-instar larva moults into a rather immobile second-instar larva, which is similar in shape, but has much shorter legs and antennae; third and fourth instars follow; the fourth feeds initially, but then stops and secretes a case around itself which bears waxy filaments. The case splits along a characteristic T-shaped line of suture (dorsally) and the adult whitefly emerges.

The citrus whitefly Dialeurodes citri is a pest of citrus, gardenia, china berry, and other plants in Florida and other gulf states of the USA.