A few days ago I was in my garden when I noticed some caterpillar damage and frass on some of the broccoli plants. I examined the leaves carefully and could not find any caterpillars. Just then I noticed on another plant a big red wasp pick up a green caterpillar and fly away with it. I had been noticing these wasps occasionally patrolling the cabbage family plants and now I know why. I was considering spending five or six bucks to buy some Bacillus thuringensis to spray the broccoli, cauliflower and cabbage, but so far there has been no more evidence of damage from the white cabbage butterfly caterpillars. For this reason I will not remove the wasp nests around out property unless one is located in an area where they are a threat to sting someone routinely passing by (These big red wasps are agressive if threatened and their stings are painfull.) I even leave yellow jackets as long as they are not in a nest near the house because they eat so many other insects.