Whitefly seem pretty impervious to w/u liquid tho it works for green and blackfly. Confidor works and is safe for tomato plants, citrus etc but bad for bees and is flipping expensive, though only a couple of cc needed in a 2litre container. It is suggested you use it AFTER 6pm or very early am.
I was looking online a few weeks ago, and one suggestion for smokers is to get all your nub-ends, soak them and use the resultant brew sprayed on. This makes sense as it contains nicotine, and I can also remember my granny and grandad using this method when I was a kid…many many decades ago