“I have a green inchworm-looking bug on my broccoli, cabbage and cauliflower. What do I do? ” This is a cabbage looper. These guys can be controlled with Bacillus Thuringiensis (BT). It is available in both liquid and in a powder form called Dipel dust. BT does not like UV light, so dust or spray BT liquid as the sun is going down and follow the label directions. You need to use a surfactant (sticker) when spraying liquid BT. Try adding 1 oz of liquid molasses to the mix and make sure you spray the under side of the leaves.
Cabbage Looper: https://insects.tamu.edu/fieldguide/cimg324.html