Natural Insecticides For Slugs
There are a number of products in local garden centers that use iron phosphate as the active ingredient. Iron phosphate, when ingested by a slug, causes the slug to immediately stop eating and then in a few days it dies.
Go to Yardener's Tool Shed to check out the natural slug killing insecticides.
Synthetic Insecticides for Slugs
There are chemical slug and snail baits sold in garden centers and hardware stores for use in traps. The active ingredient in most of them is either methiocarb or metaldehyde. If used according to the label on the package they are basically safe in the environment, though there are some reports of poisoning of dogs and cats that are attracted to uncovered baits. Birds that eat slugs poisoned by these chemicals may be poisoned as well. Another concern is effectiveness. Some research indicates that these chemical slug baits fail to kill nearly half of the slugs that they attract. Affected slugs sicken and stop eating for a day or two, but many recover.