When the hosta "eyes" appear, I mix one part household ammonia with ten parts of water and pour this mixture around the eyes close to the plant. It doesn't hurt the plants, but it does dissolve the eggs that are laid around the roots. It has reduced the slug population noticeably. I also pour the ammonia solution directly on slugs that I see on the deck. Dissolves them right away.
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, try this trick: 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..