While tasty when cooked in butter and garlic, slugs and snails can damage or kill garden plants. Garlic is, in fact, one inexpensive snail repellent; other effective repellents include organic, chemical and mechanical alternatives. From garlic to beer traps to copper barriers, there are many ways to show those slimy guys the door.
Munching its way through your flowerbeds, the common garden snail, Helix aspersa, wreaks havoc on garden plants. Pesticides based on garlic oil can be used to create barriers around plantings. According to Newcastle University biologist Gordon Port, garlic oil appears to dry up snails by causing them to overproduce mucus.
Commercial repellents are either organic of chemical-based. Iron phosphate is a naturally occurring compound sold in products such as Sluggo and Escar-Go! Repellents such as Slug-Tox and Deadline include chemical metaldehyde. Both are coated with attractactants designed to lure slugs out of your flowerbeds. Developed in the 1930s, metaldehyde is classified by the Environmental Protection Agency as "slightly toxic" to pets and other small animals.
Baits and Traps
Pan traps work by luring snails into an apparently safe environment or drowning. A slotted upside-down pie pan baited with dog or cat food makes an effective lure. Snails lured by the bait will collect underneath the pan overnight and can be discarded the following morning. Stale beer also attracts snails, or, alternatively, a mixture of boiled yeast and honey. The beer trap attracts and drowns snails, assuming the pan is high enough to prevent them from escaping.
Barriers created with scratchy substances -- such as crushed eggs, sandpaper and diatomaceous earth -- slow snails down dramatically. Copper collars make effective barriers around flowerpots and tree trunks, while copper wire protects flowerbeds. Copper does not kill snails, but prevents their progress by giving them a slight electrical shock on contact.