I fought a long and bitter battle with Cabbage White butterflies and their juicy green offspring that grew fat on the leaves of my two varieties of broccoli (a well informed gardener would be able to give you the names of the varieties - I can't). For most of the summer and autumn, I diligently plucked about 20 of the little green buggers off the broccoli every day, and gently stood on them. I also chased the butterflies with whatever tool I happened to be holding when they came near my plants.
At one stage in late autumn, it seemed as though I had lost the battle. Many of the leaves were just a ragged mass of holes, and the budding heads of broccoli had also been eaten in places. But then the cold came and the caterpillars disappeared. Suddenly the heads began growing like blazes, all over the plants. The big heads on the main stems were excellent - tightly packed flowers and very sweet. There were so many I gave some away.
With the big heads gone, little flowers start growing out of the leaf stems, and these are the gifts that just keep giving. And very convenient they are.