The damage looks like that which either the Imported Cabbageworm or the Cabbage Looper makes. The larva that is both of these is almost the same color as the cabbage leaves making them difficult to see and most often, in my experience, they will be on the underside of the leaf. Wee white moths are the adults of the Imported cabbageworm while a brown moth is the adult of the Cabbage Looper. Bacillus thuringiensis - Kurstaki will control both of these, as will Neem Oil.