I have a variety of cabbage, cauliflower, kohlrabi growing but they are succumbing to some kind of worm, I think they are cutworms but they are very small and white like tiny maggots. Any description I see of cutworms mentions one or two but there seems to be 4 or 5 per plant. is there a simple way to get rid of them? They are destroying all plants in their path.
This is likely to be cabbage root fly, which attacks all members of the cabbage family. They can only be prevented, not controlled once present.