Whitefly is a major pest in amatuer & commercial greenhouses and in large numbers whitefly can devastate plants. Commercial growers turned to a biological predator called Encarsia in the 60's and 70's and now most glasshouse crops are protected from whitefly in this way. You too can use Encarsia in YOUR greenhouse / conservatory in exactly the same way as a commercial grower.
Adult whitefly are small, white, waxy-winged insects congregate at the top of the plant, but fly off if disturbed. Both the adults and larval stages of the whitefly suck sap from the leaves resulting in stunted growth and damaged leaves. The sap contains excess sugar which is excreted by the whitefly and coats the lower leaves. Mould then develops, which is unsightly and produces poor growth. A Whitefly infestation can be brought into your greenhouse / conservatories by bringing in infected plants, so carefully inspect any new ones or they can come in through open windows / open greenhouse vents in warm weather. They are capable of laying up to 200 eggs in groups on the underside of the leaves, so numbers can build up quickly. Tiny larvae emerge ,which search out suitable feeding sites and lose the ability to move. This immobile "scale" stage is pale green, about 2mm long and lives under the lower leaves only. The life cycle consists of adult laying eggs, to larvae, to scale and finally to adult, this whole process can be completed in as little as 3 weeks in the summer. To control whitefly :-
- Control Whitefly by introducing Encarsia on small white cards, which are hung on the plants AS SOON as the first whitefly appear and the temperatures are above 10C / 50F.
- Hang yellow Glue Traps alongside plants to monitor / control whitefly alongside Encarsia.
- If the temperature is below 16C/50F, use SB Invigorator to hold the fort until temperatures rise and then introduce Encarsia.
- If the infestation is very heavy then spray with our natural spray SB Invigorator first to reduce numbers before introducing Encarsia - see our Whitefly Emergency Pest Pack.
N.B. Whitefly should not be confused with aphids, which shed their skin leaving them on the leaves. To tell the difference shake the plant, whitefly will fly off whereas aphid skins will remain stuck. If it is aphids, use aphidius / ladybirds / lacewings for control instead.