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