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How to identify it
- Snails carry a spiral shell; slugs look and behave the same way but lack the external shell. Both are mollusks, related to clams and oysters.[1][2]
- Both glide on a muscular foot that secretes mucus, which dries into a silvery slime trail.[1][2]
- Garden slugs range from 1/4 inch to 2 inches or longer and have two pairs of feelers: the larger upper pair carries the eyes and the lower pair is used for smelling.[2]
- The brown garden snail, brought from France in the 1850s as food, is the most common problem snail in California gardens. The gray garden slug is a pest worldwide, and Wisconsin finds it and the spotted garden slug the most common slugs there.[1][3][4]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Earwigs | Earwigs and caterpillars can leave similar holes in leaves, but they don't leave the silvery mucus trails that confirm snails or slugs.[1] |
| Caterpillars | Caterpillar chewing can look like snail damage; check for slime trails to tell which pest is responsible.[1] |
Where it lives
Common garden pests from California to Minnesota and Wisconsin. In mild-winter areas such as southern coastal locations they can stay active all year; farther north, slugs are active from spring to fall.[1][2][4]
Biology and life cycle
All land snails and slugs are hermaphrodites, and any individual can lay eggs after mating with another.[1]
Brown garden snails lay about 80 pearly white eggs at a time in the soil, up to six times a year, and take about two years to mature.[1]
Slugs mature in about three to six months and lay batches of 3 to 40 translucent eggs under leaves and in soil cracks. Growth varies a lot: gray garden slugs raised under identical conditions split into fast and slow growers, and Wisconsin says many slugs live more than a year.[1][3][4]
They are most active at night and on cloudy or foggy days. Numbers climb in damp, rainy weather and nearly vanish in dry spells; in direct sun without shelter, slugs quickly dry out and die.[1][4][2]
In hot, dry spells snails seal themselves off with a papery membrane, often stuck to tree trunks, fences or walls.[1]
Damage and signs
- They rasp irregular, smooth-edged holes in leaves, flowers and fruit with file-like mouthparts and can clip off small, tender plant parts.[1][2]
- Seedlings, herbaceous plants, turfgrass seedlings and ripening fruit near the ground, such as strawberries and tomatoes, are most at risk; citrus is especially susceptible. In Wisconsin, tomatoes are often damaged just as they ripen.[1][4]
- Plants they badly damage include basil, beans, cabbage, dahlia, delphinium, hosta, lettuce, marigolds and strawberries.[1][2]
- Light to moderate slug feeding usually spoils looks more than plant health, but severe feeding can injure plants, especially seedlings. Slugs seldom bother plants growing in full sun, or trees and shrubs.[2]
Health risk
Snails and slugs can carry rat lungworm, a parasite of rats. People are infected by eating raw or undercooked snails or slugs, or raw produce holding a small one or part of one. Most recover on their own, but the parasite can cause a rare type of meningitis.[5]
Control
Prevention
Switch to drip irrigation or water in the morning so plants and soil dry before evening, and favor plants they avoid, such as lavender, rosemary, sage, ferns, hydrangea, nasturtium and lantana.[1][2][4]
Keep them out
Copper flashing or screen with its lower edge buried an inch or two keeps them out of beds, and copper bands work on trunks and planter boxes. Minnesota warns that strips must be wide enough for a whole slug and that sharp edges can hurt young children.[1][2][4]
Sanitation
Remove daytime hiding places such as boards, stones, pots, debris, weedy areas and dense ground covers like ivy, and rake back heavy mulch.[1][2][4]
Traps and physical control
Handpick after dark with a flashlight, wearing gloves, daily at first and then weekly. Boards raised on 1-inch runners, shingles or inverted pots make traps: scrape off and kill the slugs gathered underneath each morning.[1][2][4]
Biological control
Penned ducks, geese or chickens can significantly reduce snails. Toads, frogs, ground beetles and firefly larvae eat slugs, and where legally allowed, the predatory decollate snail controls young brown garden snails.[1][4][2]
Pesticides
Slugs and snails are not insects, so most insecticides won't touch them. Iron phosphate baits are the safer choice around children, pets and wildlife; ferric sodium EDTA works the same way but kills faster. Scatter bait in the evening rather than piling it, and pair it with habitat changes.[4][1][2]
Metaldehyde baits are particularly poisonous to dogs and cats, and dogs are drawn to the pellets, so don't use them anywhere children or pets could reach.[1][2][6]
What doesn't work
Crushed egg shells and coffee grounds haven't been shown to deter snails or slugs.[1]
Don't kill them with salt, because it raises soil salinity.[1]
Beer or yeast traps only attract mollusks from a few feet away and need fresh bait every few days.[1]
Slug bait and dogs
Of 772 dogs in UK poison-line cases of suspected metaldehyde bait poisoning, 77.3 percent developed signs such as convulsions, twitching, tremors, drooling and vomiting, on average 2.9 hours after eating it, and 16 percent died or were euthanized.[6]
U.S. National Pesticide Information Center reports from 2001 to 2011 linked 35 dog deaths to metaldehyde and none to iron phosphate. The authors still warn that iron phosphate baits can cause iron poisoning in dogs that eat them.[7]
Rat lungworm: simple precautions
Wear gloves when handling snails or slugs and wash your hands afterward. Wash raw vegetables thoroughly, and clear snails, slugs and rats from around the house and garden.[5][8]
The parasite is established in Hawaii and has been reported in Alabama, California, Louisiana and Florida, where it has turned up in introduced snails. Its known range now includes the southeastern United States and the Caribbean.[9][10][5]
Where sources disagree
Winter: UC IPM says snails and slugs hibernate in the topsoil; Minnesota says slugs mostly overwinter as eggs that hatch the next spring; Wisconsin says as adults or eggs.[1][2][4]
Iron phosphate safety: Minnesota says it poses no problems around children and pets, while a veterinary study of poison-line reports describes suspected iron poisoning in dogs that ate it, though no deaths.[2][7]
Diatomaceous earth: UC IPM says a dry band can work but fails once damp; Minnesota calls it generally ineffective.[1][2]
Common questions
- How do I know snails or slugs are eating my plants?
- Go out at night or early morning to catch them feeding, and look for shiny slime trails near the damage.[1][2]
- Are slug baits safe around pets?
- Iron phosphate baits are the safer choice, though a veterinary study notes they can still cause iron poisoning in dogs that eat them. Metaldehyde baits are far more dangerous to dogs and cats.[1][7][6]
- Is it safe to touch garden snails?
- The CDC advises wearing gloves when handling snails or slugs and washing your hands afterward, because they can carry rat lungworm.[5]
- Do beer traps work?
- They catch some, but only from a few feet away. Bury the container with its rim at ground level and refill it every few days.[1][2]
Sources
- University of California Statewide IPM Program, “Snails and Slugs (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/snails-and-slugs/ (accessed 2026-11-11)
- University of Minnesota Extension, “Slugs in home gardens.” extension.umn.edu/yard-and-garden-insects/slugs (accessed 2026-11-11)
- Insects, via PubMed, “Shirley, Howlett and Port (2020), Not all slugs are the same: variation in growth and development of the slug Deroceras reticulatum.” pubmed.ncbi.nlm.nih.gov/33138240/ (accessed 2026-11-11)
- University of Wisconsin-Madison Extension (Wisconsin Horticulture), “Slugs.” hort.extension.wisc.edu/articles/slugs/ (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “About Rat Lungworm Disease (June 24, 2024).” www.cdc.gov/angiostrongylus/about/index.html (accessed 2026-11-11)
- Veterinary Record, via PubMed, “Bates, Sutton and Campbell (2012), Suspected metaldehyde slug bait poisoning in dogs: a retrospective analysis of cases reported to the Veterinary Poisons Information Service.” pubmed.ncbi.nlm.nih.gov/22859414/ (accessed 2026-11-11)
- Journal of the American Veterinary Medical Association, via PubMed, “Buhl, Berman and Stone (2013), Reports of metaldehyde and iron phosphate exposures in animals and characterization of suspected iron toxicosis in dogs.” pubmed.ncbi.nlm.nih.gov/23600781/ (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “Preventing Rat Lungworm.” www.cdc.gov/angiostrongylus/prevention/index.html (accessed 2026-11-11)
- Journal of Parasitology, via PubMed, “Stockdale-Walden and others (2015), Angiostrongylus cantonensis in introduced gastropods in southern Florida.” pubmed.ncbi.nlm.nih.gov/25564891/ (accessed 2026-11-11)
- American Journal of Tropical Medicine and Hygiene, via PubMed, “Cowie, Ansdell, Panosian Dunavan and Rollins (2022), Neuroangiostrongyliasis: global spread of an emerging tropical disease.” pubmed.ncbi.nlm.nih.gov/36343594/ (accessed 2026-11-11)
- iNaturalist, “Cornu aspersum taxon page (order and family).” www.inaturalist.org/taxa/480298 (accessed 2026-10-06)