Having trouble with whitefly?

Cover a white or yellow strip of plastic with oil--engine oil or cooking oil-or vaseline -anything sticky.  Hang the bag just above your plants and the whitefly will land on it when they are disturbed and stay stuck.  This catches thrips too quite spectacularly as being black they show up clearly,.

 If you use an old supermarket bag    to provide   the plastic you will   have an extremely cheap throwaway trap