Stopping Glasshouse Whitefly killing your plants Glasshouse Whitefly: Control with Encarsia Parasite Small, white, flying insects with sedentary larval stages (scales) which feed on plant sap weakening the plants. The scales, which produce copious amounts of honeydew, are difficult to see, being a light creamy colour. Indoor crops are vulnerable, with tomatoes, cucumbers, fuchsias & soft-leaved ornamentals being examples of the most susceptible hosts. Control with Encarsia parasite: Tiny parasitic wasps which lay eggs in the whitefly larvae. The Encarsia larva kills the larvae which turns black before a new adult Encarsia emerges via a small round hole. Introduce as soon as whitefly are seen. Needs temperature of 15-18?c for a few hours each day. Repeat applications are advisable if the problem is severe. Having trouble with garden pests? These biological control products will ensure that pests stop killing your plants.