There are a number of natural solutions.
Here is one:
Crack Open a Cold One
Slugs like beer as much as they like the leafy greens of your garden plants. Crack open a beer and pour it into a few margarine tubs, then distribute the containers in various places around the yard, burying them so that about an inch remains above ground. The slugs will be attracted to the scent, crawl into the tubs, and drown overnight. Dispose of the containers the next morning in your trash or compost bin. (HT Bob Vila)