If by cut worms you mean the green, fleshy worms that feed on cabbage and cole crop than this is the larvae of a the white cabbage butterfly and covering your crops with and agricultural fleece like Remay will keep the butterfly from landing in the spring and depositing her tiny eggs - which hatch into the green worms. There are other larvae that are white, or gray some tiny and some large and if you can send a photo I will be more accurate at trying to identify the specific pest. Keep growing, Marianne Binetti