I have little green caterpillars eating my broccoli leaves. I used a garden dust "seven" and then the next day I saw a large amount of green caterpillars all on the ground dead or dying under the plants. I watered with miracle grow liquid vegetable food to get all the dust off all the plants. What do I do about the almost fully eaten leaves? Do I dust again in a few days? This is my first real garden and these are things I'm not sure on.
You will need to use an insecticide with Bt.
Here is a link with more information.