I just had a look at the broccoli and cauliflower plants in my garden and noticed that the leaves have been severly effected by pest damage. Upon closer inspection there appear to be green worms or catapillers about 1 inch long on some of the plants. I googled the worms and they appear to be either cabbage worms or diamond back worms. A few suggestions I've read was to either sprinkle with diatomaceous earth or to spray with BT.
I've picked off what I could see but I'm sure they'll be back. What can I do to save them?