white flies on my lettice.

[strawberriesandcream01]

My lettice plants are outside and are covered in white flies. How can i get rid of them please?

Three ideas to try:

FREE... spray dilute washing up liquid onto plants

CHEAP...organic oil spray

COSTS A BIT,NOT A LOT...encarsia is a parasitic wasp which you can buy for your greenhouse they only work at temps above 16c (Tamar organics, the organic gradening catalogue - both have websites)