A good cure for any pest is the good old rhubarb leaves ,get a water but and put the leaves in with the water leave for a week give it a good stir leave for a couple of days then water the plants with it, white fly hate it Caterpillar hate & it deters butterfly's and moths, carrot root fly hate The smell too.
The leaves of the rhubarb are toxic & give off a bit of a whiff to passing pest. don't worry though it is safe as the toxins break down after 24hrs but the magic whiff still lingers.
i did an experiment last year with my cabbage & yep you guessed it the half i did not water with the magic mix got eaten & what a white fly infestation i had, ended up pulling up all the plants.
Even the pesky wasp which until now had no use on this planet what so ever!! but they do the eat greenfly!.