Slugs: Identification, Control & Prevention

Slugs are soft-bodied mollusks (not insects), related to squid and clams. Hermaphroditic; complex mating. Thrive in moist, humid climates; worse in rainy seasons. One lung; reduced shell plate.

Identification

• Gray to dark brown, ~1". Hide in dark/damp by day.
• Nocturnal feeders; hard to spot.
• Slime trails on plants/soil—visible mornings.
• Monitor: dig 4"x6" holes, cover with board, check in 3 days.
• Eggs in moist soil/compost; populations explode in cool/wet.

Damage

Irregular holes, ragged edges (file-like mouthparts). Seedlings consumed entirely. Favor beans, lettuce, cabbage, tomatoes.

Control

• Board traps: Morning flip, scrape into containers, freeze 3 hrs, compost.
• Beer traps: Shallow dishes or modified bottles (funnel in) to prevent escape. Molasses/cornmeal/yeast alternatives.
• Hand-pick: Evening twilight or dawn.
• Barriers: Wood ashes (potassium source), diatomaceous earth, copper sheeting, coffee grounds, pine needles, coarse sand, crushed eggshells—rip tender undersides.
• Alcohol spray: Equal parts 70% alcohol + water (or 1:1.5 for 95%).
• Cold coffee spray: Must drench completely.
• Resistant plants: Astilbe, phlox, mint tolerate slugs.
• Old remedies: Oak leaf mulch; lettuce/spinach/cabbage/potato slice traps overnight; frogs/toads eat slugs; alkaline soil (slaked lime, ashes, sand, cinders) repels.

Prevent slug damage with above tips.

Prevention

• Early spring raking removes moist debris/eggs. Avoid large wood chips.
• Water only when necessary.
• Encourage predators: chickens/ducks, snakes, turtles, frogs, toads, ground beetles, firefly larvae, songbirds.
• Copper tape perimeter—slugs get mild shock.
• Trap crops: chervil, marigold, thyme near valuables; destroy infested.