I still find the sticky yellow plastic cards one of the most effective and least toxic methods. Hang them just above the infected plant and every time you pass the plant, brush it with your hand making the white fly fly up. A lot of them will get stuck on the card.
There is a biological control too which is a tiny almost invisible wasp which parasitises the eggs of the white fly. This will eventually eradicate the white fly entirely if used early enough, although it will only work in a greenhouse rather than outside.
Persevere with the sticky yellow traps and you will find this controls them well although they won't entirely eliminate them.