Each time you crack an egg open, instead of tossing the shell into the trash, drop it into an open container that you keep in the fridge. When the container is full, crush the shells into small bits and sprinkle them around the base of your plants. The sharp eggshells will deter slugs, snails, and other bugs from nibbling on your garden and add a touch of calcium to the soil.
To get rid of ants, put small piles of cornmeal where you see ants. They eat it or take it home to the others. They cant digest it so it kills them. It may take a week or so, especially if it rains, but it works and you dont have the worry about pets or small children being harmed!