Despite their slow movement and lack of teeth, slugs are a formidable foe in the garden. They are able to re-grow their heads, are hermaphroditic (having both make and female sexual organs) and their eggs can lie dormant in moist soil for many years. So, control of slugs is an on-going battle for the gardener, but one that is very winnable with less-toxic methods such as hand harvesting, trapping and baiting with pellets.
Low Tech Method
Hand picking of slugs is still the primary tool in any slug-fest. Lay boards, overturned ceramic pots and spent grapefruit halves in the garden soil before dusk. Sprinkling water around the slug shacks will make them irresistible to passing snails. In the early morning, tip-over the boards, pots and grapefruit and drop the resting slugs into a coffee can or yogurt container. (In my own experience, when I dropped live slugs into a pail, without a lid, thinking that they would drown, they simply crawled out eventually. Only when I began adding a few drops of dish soap to the water, would they succumb and die. So I just pour the slugs and water onto the compost pile.)
Also, the snails can be recycled into the farm pond as fish food, or their slime can be used for chafed skin.
Dig a shallow depression in the garden, sink an aluminum pie pan so that its lip is at soil level, and fill with beer, or a soup of yeast, molasses and water. Slugs will crawl into the plate, not be able to escape and will drown.
Note: this method works best if your garden is fenced or if you do not have a pet that may drink the bait liquid.
For a more pet-proof trap, cut a 1” hole in an empty coffee can, sink the can into the ground so that the hole is at soil level, fill with bait liquid and replace the can lid.
Sticky traps can be laid along slime trails, however, they should be used sparingly as they also snare lizards and frogs, both of which are very beneficial to the garden.
Iron Phosphate pellets, available at markets, hardware and garden centers, can be scattered in the garden, killing snails about 6 days after ingestion. Although company advertisements claim complete safety for pets, wildlife and humans, care should be taken not to expose pets or children to the pellets.