Non-Toxic Slug Management Strategies
We have imported many different species of slugs into our geographic area.
Commercial slug baits come in forms like granules and emulsions. The most commonly used ingredient is metaldehyde, which kills slugs and snails, but can lead to nervous system damage or death in humans and pets. Here are pages and pages of safer alternatives.
Slug Prevention:
1. Don’t introduce slugs to a new area! Don’t bring them in with landscaping material, plants, transplants, firewood, or compost-making material like grass and leaves from slug-infested areas.
2. Don’t give slugs any prime real estate. They retreat under dark moist places like stacks of firewood, leaf piles, potted plants, hoses, and rocks. This is where they lay eggs, too. Remove the slug habitats –their sheltering cover and wet areas.
3. This means remove your mulch from around crops. Sigh…it’s a shame because mulch is so beneficial to the soil!
4. Slugs love your compost piles, so sprinkle a band of wood ash around the perimeters after each rain. Slugs don’t like wood ash, so it slows them down from entering your piles.
Slug Management Strategies—Killers and Repellants: Aw shucks! No one treatment works with all slugs. You’ll have to do multiple management methods simultaneously.
Hand-pick slugs regularly. The slugs would deeply appreciate a quick merciful death and without hate. Please do not torture them or get vindictive. So perform a quick smash, or feed them to chickens or ducks, or drop slugs in a container of heavily salted water.
Patrol with ducks and/or certain breeds of chickens: Ducks are very effective hunters. They are your absolute best elimination method for slugs and slug eggs. They are on duty every day!
Till or cultivate in the spring and in the fall to bury slug eggs.
Sprays:
1. Hunt and spray the tiny slug eggs in the spring. Use ammonia solution of 4 parts water to 1 part household ammonia.
Note: After using sprayer, spray plain water through it to remove corrosive ammonia residue. This preserves the metal nozzle.
2. Hunt and spray adults during the growing season with one of the following:
—Ammonia: Make a solution of 2 parts water to 1 part household ammonia for baby slugs. Ammonia will fertilize soil if not too strong a solution.
—Household vinegar: Mix it with equal volume of water. Apply as spray on lower leaves and base of your plants. Vinegar will “burn” plant leaves if your formula is too strong.
—Coffee: USDA says spraying plants plagued with slugs with will kill slugs in 2 days. The caffeine in any form — including a few No-Doz tablets mixed with water — is a slug neurotoxin that will kill these pests eventually.
—Ammi Majus: Make these flowers into an herbal tea and spray (Mother Earth News Feb-Mar 06 p. 53)
—Dr. Bronner’s Peppermint Pure Castile Soap: one capful in a 1-quart spray bottle. Spray plant and soil around it once a week. This spray also works on earwigs, aphids, spider mites, ants, and mealy bugs. (From a commercial lettuce grower in the Northwest.)
Traps:
Lay out these materials as night time gathering places for the slugs. Check traps and kill the slugs each morning. Clean & refill the traps often.
• Boards on paths. Turn them over and squish slugs daily.
• Boards or cardboard with Tanglefoot (a sticky substance sold at garden stores) spread on it.
• Wilted vegetables and cabbage leaves on paths.
• Grapefruit domes.
• Beer in open containers (make it FRESH beer, refreshed every 24-48 hours). King’s Malt brand works well. Slugs drown.
Or yeast-water solution: Into a pint plastic container as a trap: 1 cup water, 1 tsp sugar, 1 tsp flour, ½ tsp dry yeast. Sink containers to soil level and cap over loosely to protect from rain and soil. Slugs drown.
Repellants and Barriers:
Sprinkle a “fence” or border of one of these to repel slug migration. Slugs have sensitive skin and don’t like gritty or coarse substrates. Remember that slugs can navigate over almost anything that’s wet with rain or irrigation water.
Ash from woodstoves. Slugs find ash distasteful. Replenish after irrigating or rainfall.
Window screen: Lap an 8-inch wide strip of metal window screen over the edges of wooden raised bed frames, and staple them in place. Slugs don’t like crawling across this material.
Crabgrass cookies: mix chopped, dried crabgrass leaves with corn bran, cornstarch, and beer. Place bait beneath plants, where the slugs eat them and die. (This source said crab grass. Try it with quack grass if you have it.) For more information, see page 4.
Cedar chips. Surround the outside edge of your garden or compost area. Don’t put cedar chips directly around plants, since compounds in the cedar may inhibit plant growth.
Coffee grounds due to the residual caffeine.
Roofing shingles- the gritty kind.
Copper strips. Rolls are sold in garden stores with adhesive backing. Stick them on as a barrier around raised bed frames and borders of garden.
Copper pennies on pots. Slug-proof outdoor potted plants by caulking on some pennies on outside of pots.
Crushed eggshells. Dry them for 24 hours first to be effective.
Crushed oyster shells. Often oyster shell is sold as chicken layer blend in ¼ th to ½” chunks.
Diatomaceous earth (DE) or DE plus alum. Alum is aluminum sulfate salt. Apply at a rate of 4 parts DE to 1 part alum. Sprinkle as dry mix or mix with water and spray the “tea”. Note: DE sold for swimming pool filters is not the same as the kind sold for pest control. DE comes from fossilized remains of tiny algae called diatoms. The substance either absorbs the insects’ oily or waxy outer cuticle, or its spiked surfaces abrade the slug’s protective “skin”. Thus DE is effective for insects too. DE will also tear up human lungs, so always wear a dust mask when mixing and applying DE.
Hair: from humans and dogs. Also, try sheep wool, which has natural oils that do not mat in the rain. These are reported to remain effective for 2-3 years.
Pine or spruce needles.
Quack grass (Agropyron repens): Dry the leaves and stems, and then sprinkle them around the plants lightly. The drying brings out the slug-specific toxin that the quack grass contains. Apply sparingly; as quack grass contains allelopathic compounds that can be suppress growth in the garden plants you’re trying to save. Researcher Roger D. Hagin at Cornell University recommends experimenting in a few places and applying 6 grams of dried quack grass per square foot; or no more than 2 ounces of dried quack grass per 10 square feet.
Quack grass cakes: Mix 1 oz of corn bran, ¾ oz of powdered milk, 1 oz corn starch and a pint of beer with 8 oz of dried quack grass. Make a paste that will form a pellet. Run the thick dough through a meat grinder to create pellets. Then air dry them. Spread the pellets in a band around the perimeter of seedling beds; the slugs will be attracted to the beer bait, and end up eating the toxic grass. Within 30 minutes of spreading such pellets in fields in New York, all of the slugs present began feeding on the pellets, reports Dr. Hagin. In an area where slugs numbered 78 per square meter following a heavy rain, the number dropped to one slug per square meter 30 minutes after the baited pellets were applied. The pellets remained effective for about a week. Note: do not plant quack grass on your property if you don’t have any. Harvest from nearby fields and edges. (From Organic Gardening, May/June 1997.)
Sawdust, the more coarse the better.
Stone wall that is 5’ high (Helen Nearing).
Lime (ground limestone). Replenish after rain or irrigating.
Sharp sand or volcanic ash.
Crushed shells of filberts, pecans, English walnuts, or chestnuts.
Corn meal: Put a tablespoon or two of cornmeal in a jar and lay it on its side wherever there is slug activity. The slugs love this stuff. After eating it, they die (in bliss?).
Salt, but sprinkle with care, as you may damage your plants and soil microbes.
Salt strips: (salt-embedded plastic strips) Make some; it’s uncertain where to find them made up commercially at this time.
Sluggo, a commercial product, is iron phosphate. Apply 1 level tsp per square yard, or 1 pound per 1000 sq. ft. To order a large quantity: Monterey Lawn & Garden, Fresno, CA. www.montereylawngarden.com
Other repelling substances and strategies that I have read about but have not tested personally:
Geranium leaves, mint, horseradish roots, scatter bird seed in garden to attract slug-eating birds, scatter red leaves at base of plants; slugs reportedly don’t like red; also plant red varieties of chard, lettuce, and cabbage; plant a border of mustard as a trap crop.
Add your own and add chickens or ducks to your system if you can. They are your best hunters & managers.