More ideas from Emm
Make a 50/50 combination of flour and baking soda, and dust it all over whichever plants the cabbage worms are eating. They'll eat the combo while munching the leaves, and die within a day or so. Repeat as necessary..

Alternative Gardning: Controlling Cabbage Worms - (Gross) - Sprinkle Baking Soda on Cabbages (and other Brassicas) to Thwart Caterpillars If those small green cabbage worms have been making Swiss cheese of your cabbage, broccoli, and kale plants