Trialeurodes vaporariorum - when young, they appear as small, scaly creatures on the underside of leaves. These scales protect them from all insecticides. The more adult whitefly look like tiny white moths, and they will make short circular flights when disturbed. They are transparent to opaque and vary in colour from creamy white through to brown.
How to Treat White Fly
Spray with 'permethrin' - this is a naturally occurring insecticide which is harmless to human beings and the beneficial wildlife in the garden. It is available at almost all garden centres and DIY stores.
It is also possible to reduce the numbers by spraying with very diluted washing up liquid but permethrin is far more effective.
Spray as soon as the flies are noticed - three sprays over ten days should see them off. This will kill the young white fly after they emerge from their scales.