Pests and diseases - White Fly

Signs - Most commonly found on houseplants and in greenhouses, when disturbing the leaves, the tiny white flies that hide under the leaves will fly up.

Damage - Sap suckers, will weaken the plant and make it susceptible to further attacks of pests and disease.

Treatment

   Tap the leaves and, as a cloud of flies up, suck them up with a small car vacuum cleaner - take care! or you'll damage your tender little plants.

    Whiteflies are also attracted to yellow paper, so you could try hanging strips of sticky yellow card which the whitefly stick to - these are available commercially and if you think you have whitefly will become covered surprisingly quickly. They also serve as a good early warning for if you suspect that you will get whitefly.

    Avoiding whitefly on tomatoes without the use of chemicals.  Plant French Marigolds (Tagetes) between your tomato plants to keep those pesky Whitefly away. It's not that the Whitefly particularly don't like these marigolds, it's because the pungent smell from the marigolds masks the nice smell of the tomatoes that usually attract the Whitefly.

    Another option is to go for biological control. Biological control of a pest relies on introducing a predator species so "fighting nature with nature", if chosen carefully, the predator will stop damage to your plants without damaging the environment. Such biological controls are safe for the user, children and pets. They will not harm other beneficial garden insects and are biodegradable.

The biological control for whitefly is the parasitic wasp, Encarsia formosa. These minute little wasp's parasitise the whitefly pupae. Encarsia is only suitable for glasshouses and conservatories. Encarsia needs a 24 hour average temperature in the glasshouse of at least 17°C