Encarsia formosa

This insect is related to the wasp - but it is much much smaller, and it does not sting humans, it "stings" whitefly larvae. It is so effective that it is now the professional growers choice for controlling whitefly in glasshouses.

Encarsia is supplied as unhatched "pupae" or "scales" which are stuck onto a card, so that they can be conveniently hung around among your plants. The pupae will hatch out at intervals over the following week and the tiny insects then fly through the crop searching for whitefly larvae. The encarsia females lay eggs actually within the larvae, and when the egg hatches it consumes the whitefly from within. Initially it feeds without killing its host, so that the whitefly continues to feed and grow, but as the host larva reaches maturity and ceases to feed, the parasite attacks the vital organs. At this point the whitefly scale turns black, and about eight days later a new Encarsia emerges to repeat the process. 

Encarsia works best with temperatures above 21°C with 12hr+ daylight hours. Generally, this means introducing Encarsia from mid April to August, although it can be earlier or later with extra heat and light. They will stay with their prey within a greenhouse, but are not suitable for applying outdoors

The Standard pack (5 cards) should give good control for an average conservatory or small greenhouse. If you have a longstanding battle with whitefly order two packs with separate delivery dates. Then you can follow up the initial treatment with a second introduction two weeks later.

The Larger pack should be used if the Whitefly infestation is very bad or the area large. .