COMMON NAME
Greenhouse whitefly
Order

Suborder

Family

Genus

Species

Alias
Hemiptera

Sternorrhyncha

Aleyrodidae



Trialeurodes vaporariorum

Glasshouse whitefly

Description

Although called whiteflies, they are not related to “true flies” (dipterans). They have the characteristic piercing and sucking mouthparts of the Hemipteran order. Whiteflies are tiny, white, moth-like insects which are related to aphids. Their wings and bodies are covered in a white powdery wax. This may be why they were given the family name Aleyrodidae which means “flour like”. The greenhouse whitefly can be distinguished from the silverleaf whitefly by its wings, which slightly overlap. There is a distinct separation of the wings in the silverleaf whitefly. They are usually in great numbers and when disturbed they will fly up in a cloud. The nymphs are oval and flat and look like scale but are very difficult to see as they blend in with the plant they are on. Early nymphs will move around but later stages do not, remaining in one spot till they pupate. The eggs, laid underneath the leaves and often in circles, are small, oval with a yellow tinge turning a darker grey-purple colour near to hatching.

Adult size: 1-2mm

Out and about

Most numerous in warmer weather particularly summer through to autumn. Very common in greenhouses as they like the warm dry conditions and protected environment. Found throughout temperate regions of the world. In Australia it is more prevalent along the east coast up into the tropics but is also found in other temperate regions.

Reproduction and Life cycle

Each female can lay up to 200 eggs which will hatch in 1 week. Their life cycle ranges from 4-8 weeks depending on the weather conditions, being shorter in warmer weather. They can produce many generations over the year.

To deter

Pineapple sage, mints and bee balm have strong scents that make it difficult for pests to detect other plants

To control

- attracted to yellow, so can be trapped by smearing a yellow surface with Vaseline or other sticky spread - Citronella spray will deter adults from landing on plant - White oil sprayed regularly, on the nymphs and the flies if possible, will smother them - Spray with neem oil - Spray with pyrethrum

Plants to repel

Artimisias / Basil / Thyme / Calendula, marigolds, nasturtiums (yellow) and mint can be grown as trap crops (attract whitefly away from food crops)

Plants to attract

Predators

Lady beetles / Lacewing / Encarsia wasp / Predatory mite / Hoverfly / Damsel bug
Why they are a Pest
Both adults and larvae are sap sucker of the leaves, causing leaf loss, wilting and stunted growth. Their larvae also excrete honey dew which attracts ants and causes sooty mould. Like aphids and scale they can spread viruses. They attack a wide range of plants particularly liking hibiscus, herbs and vegetable seedlings. In large scale agriculture they are a pest of cotton, sunflower, soybean and navy bean. The greenhouse whitefly is not as bad a pest as the silverleaf whitefly Other signs of whitefly attack are silvering and yellowing of the leaves, uneven ripening of fruit and the presence of sooty mould.
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