Each night there are likely hundreds of them slithering around my property eating several times their body weight in the period of nine hours.
There are approximately 40 species of slugs known in North America, most of which have been introduced accidentally.
The cool, moist days of early spring are ideal conditions for them. They emerge from their hiding places in late evening and are most active during early morning hours before the sun rises, traveling a distance of approximately three feet overnight.
Slugs reproduce faster on alkaline to neutral soils than on acid soils. Although it seems that most of the damage occurs in spring, the maximum seasonal feeding and mobility occurs in October and November.
I once interviewed an organic gardener who told me that she, along with several gloved helpers, picked over 2,000 slugs from their garden after dark during a two-week period. Trap crops, like hosta or plantain, can help concentrate your efforts. If you have an old blender you can blend up your slug harvest, add water and spray this back onto your ornamentals. Some gardeners claim that this “bug juice” repels slugs.
A few other ways to get rid of them include the old set-up-the-bar trick. Place a shallow saucer of beer in the garden. Some people find one teaspoon of baking yeast in three ounces of water to be even more effective. Hollowed out halves of grapefruit or cantaloupe can attract slugs for disposal.
Horsetail, a primitive plant that grows by the roadside can be used to make a spray. Boil one to two ounces of dried herb in one gallon of water and simmer for 20 minutes. You can add cayenne pepper as well. The high silica content of the horsetail and the aconitic acid it contains, is said to repel slugs.
Diatomaceous earth, a fine powdery material made from the shells of microscopic sea creatures called diatoms, acts like tiny razor blades on soft bodied slugs. Crushed eggshells act in the same way. Once slugs are injured, they dry out and die. Diatomaceous earth has to be re-applied after every rain.
Barriers have also proven to reduce damage from slugs. Strips of copper flashing will actually deliver a mild electrical charge to slugs if they touch it. If your crop is in a raised bed you can fasten three-inch wide strips of aluminum screening around the perimeter. Unweave a few strands and bend the exposed strands to face outward.
Salt is a classic enemy of moisture loving slugs. Petroleum jelly coated with salt works very well to stop them. You can coat boards or paving stones with this concoction. Sharp sand or wood ashes discourage slugs as well