Horrid little white flies have set up home on my chilli plant in the kitchen window sill. They had started to go on the window sill itself, and also my peace lily. Chilli plant is about two feet tall. Do I really have to clean each leaf individually to get rid? The leaves are quite sticky and I remember this being a biggish yucky task last time. Is there anything I can do to discourage whatever it is in the first place? TIA.