Instead of the pyrethrum spray switch to a soap spray to kill the whiteflies. They'lll be back.
It doesn't burn and it is very effective at killing whatever whiteflies it hits. Spraying to the point of saturation and runoff with lights on or off has never burned leaves in my garden.
Make some sticky traps to help monitor the whitefly population. Link is in my signature.
Who's that long haired freaky person over there?
