These mollusks are found throughout North America, particularly in moist, temperate climates. Snails require calcium for their shells, so are less common in areas where this mineral is lacking. Slugs are gray to black or brown and soft-bodied, often with soft hump in center; snails have a hard calcium shell. Both snails and slugs feast on just about any plant, especially young tender transplants, leafy vegetables, and succulent plant parts. Their presence is indicated by large irregularly shaped holes in the leaves of plants and shiny slime trails. They are active mostly at night and in wet weather. Slugs and snails are very prolific; individuals of some species lay up to 500 eggs per year.
If there's one garden pest that's universally despised, it's slugs. Not only do they eat prized vegetables, herbs, and flowers at night while you sleep, but when you do catch them, they're so slimy and squishy that many gardeners won't even touch them, let alone kill them. However, slugs can be outwitted.
Barriers Being soft-bodied creatures, slugs don't like anything sharp. If cut, they often will dry up and die. Sprinkle sharp sand, diatomaceous earth, or dried, crushed egg- or oyster shells around favored plants. Refresh the materials after heavy rains. If you have a raised bed, permanent border, or container, fasten strips of copper flashing around the bed. When slugs come in contact with the copper, they get an electric shock. (Think of it as an electric fence for slugs.)
Traps Using slugs' propensity for hiding in the dark, place boards on garden pathways. Early in the morning, turn over the boards and knock the slugs into a bucket of soapy water. Slugs also like beer (actually, the yeast in beer). Create a slug trap by sinking an empty coffee-can-sized container into the soil to the soil line and filling it with beer. At night the slugs will dive in to feast and eventually drown. Clean out the trap in the morning.
Baits Although the commonest slug control baits contain the slightly toxic chemical metaldehyde, some new baits, such as iron phosphate, are less toxic to animals and humans. Any bait will have to be reapplied after a rain, and you should be careful not to sprinkle baits where pets and young children can find them.
Slugs cause the most damage on young plants, so make extra efforts to protect them.