Scientific Name

Trialeurodes vaporanium

Common Name

Whitefly

Phylum, Class

Hemiptera, Aleyrodidae

Physical Description

[C1] 2mm long, pure white adults, have two pairs of wings folded over the back of the abdomen at rest. [C2] Nymphs crawl over plant soon settle and feed, becoming immobile scales.

Distribution, Habitat

A tropical subspecies introduced into Britain. Lives only in greenhouses, interior landscapes.

Life Cycle

Adults live for a month. Female will lay 200 eggs in that time. in neat circles on underside of leaf. Eggs harden after laying and hatch in 10 days. Nymphs crawl over plant and then settle, legs and antennae degrade, and become immobile scales, and feed for two weeks before entering a non feeding pupal stage from which adult emerges. Egg development to adult takes 3 weeks at 21C and longer in lower temperatures. Breeding continuous in glasshouses. Killed outdoors.

Method Of Attack

Sucking of sap from leaves and cells of plants.

Symptoms

Adults, eggs and scales present on the undersides of leaves. Upper surfaces may be fouled with honey dew and sooty moulds.

Damage Caused

Plants will reduce vigour, and look unsightly, yellow spots and discoloration occur.

Plants Attacked

Tomato and Cucumber, severely. Also attacks glasshouse plants and house plants. These include Abutilion, Begonia, Fuschia, Heliotrope, Hibiscus, Chrysanthemum, Coleus, Dahlia, Pelargonium, Primula, Salvia, Verbena

Chemical Control

Prevent serious damage by examining plants. If adult or immature stage seen, use:
Contact Spray: Malathion, HCH, Pyrethrum, Bioresmethrin or a
Systemic insecticide: such as Dimethoate or Formathin, twice at weekly intervals.
Fumigants: HCH, Dichlorus, kills adults, is becoming resistant.

Biological Control

Parasitic Hymenoptera, Encarsia formosa. Good results at 21C> in commercial glasshouses. Introduced on leaves bearing parasitic scales, available for a restricted period when supplies are available. Persistent insecticides and HCH should not be used then.

Stage Vulnerable

Adults and nymphs.