Slugs

Common Types of Slugs

The slugs you are most likely to find in a Virginia or Maryland yard are the gray field slug, the leopard slug, the yellow slug, the dusky slug, and the native Carolina mantleslug. The University of Maryland Extension names the gray field slug, the yellow slug, and the leopard slug as the three common garden slugs in Maryland. The other two show up in damp woods, mulch beds, and under logs.

Use this chart to narrow it down, then check the notes on each type below.

Slug	Adult size	Color and pattern	Where you find it	Best ID clue
Gray field slug (Deroceras reticulatum)	About 1 to 2 in	Cream to gray-brown with darker mottling	Vegetable beds, lawns, seedlings	Small, net-like mottling; milky white slime when touched
Leopard slug (Limax maximus)	4 to 6 in, sometimes more	Gray to tan with black spots and stripes	Foundations, basements, woodpiles	Large size and bold spots, like a leopard
Yellow slug (Limacus flavus)	3 to 4 in	Yellow to orange with gray-green mottling, blue-gray tentacles	Cellars, crawl spaces, compost, near houses	Yellow body and yellow slime
Dusky slug (Arion subfuscus)	2 to 3 in	Brown to orange-brown, darker bands on the sides	Woods, leaf litter, shaded beds	Orange-yellow slime that stains your fingers
Carolina mantleslug (Philomycus carolinianus)	2 to 4 in	Tan or gray with two rows of dark spots down the back	Under loose bark and rotting logs	A smooth mantle covering the whole back
Marsh slug (Deroceras laeve)	Under 1 in	Plain brown, no pattern	Wet soil, pond edges, greenhouses	Tiny and very active

Gray Field Slug

The gray field slug (also called the gray garden slug or netted slug) is the slug that does most of the damage in home gardens. It came from Europe and now lives in most of the United States. Adults are about an inch or two long. They are cream, gray, or light brown with a darker net of mottling. If you touch one, it gives off a thick, milky slime. These are the slugs chewing holes in lettuce, hostas, strawberries, and new seedlings.

Leopard Slug

The leopard slug is the big one. Adults often reach 4 to 6 inches long. They are gray or tan with black spots on the front shield and black stripes or spots down the body. They hide under boards, woodpiles, and in damp basements, and they come out at night. Leopard slugs eat fungi, dead plants, and even other slugs, so they cause less garden damage than you’d guess from their size.

Yellow Slug

The yellow slug (Limacus flavus), sometimes called the yellow cellar slug, lives close to people. It is 3 to 4 inches long, yellow to orange, with gray-green mottling and pale blue-gray tentacles. Its slime is yellow. The Carnegie Museum of Natural History lists it from gardens, waste piles, and buildings, and it has been recorded in Maryland. If a slug keeps turning up in your basement or crawl space, check it against this one and the leopard slug first.

Dusky Slug

The dusky slug is a mid-sized brown or orange-brown slug from the Arion group. It has darker bands along its sides and leaves a sticky, orange-yellow slime that can stain skin. It prefers shaded beds, leaf litter, and the edge of the woods. The large European black slug (Arion ater) belongs to the same group. It can be black, brown, or orange.

Carolina Mantleslug

The Carolina mantleslug is a native slug. Its mantle, a smooth skin flap, covers its whole back instead of just a patch behind the head. It is tan or gray, with two rows of dark spots running down the back. The Carnegie Museum records it mainly in Virginia’s coastal plain, with some piedmont populations. It feeds on fungi and lichens and spends dry spells under loose bark and rotting logs. It is not a garden pest.

Marsh Slug

The marsh slug is small, often under an inch, and plain brown with no pattern. It moves fast for a slug. You will find it in wet soil, near ponds and downspouts, and in greenhouses. When people search for a “tiny slug” or “small black slug,” this or a young gray field slug is usually what they found.

What Does a Slug Look Like?

A slug looks like a snail without a shell. It has a soft, wet body that tapers at the tail. Most adults are 1 to 5 inches long. On the head are two pairs of tentacles. The top pair holds the eyes. The lower pair smells and tastes. Behind the head is the mantle, a raised patch of skin with a small hole on one side. That hole is the breathing pore. The whole body is coated in mucus, and the slug leaves a shiny slime trail wherever it goes.

What separates slugs from look-alikes:

• Garden snails have the same body, but carry a coiled shell. See our garden snail guide.
• Leeches and flatworms have no tentacles. Slugs always have tentacles on the head.
• Millipedes and caterpillars have legs. Slugs have none. They glide on one muscular foot.

What Color Are Slugs?

Slugs come in gray, brown, tan, cream, black, yellow, and orange. Some are a single color. Others are spotted, striped, or mottled. Color alone is a weak clue, because the same species can be lighter or darker depending on age and diet. Size, the pattern on the mantle, and the color of the slime are better clues.

Slugs in Virginia and Maryland

Slugs here are worst in spring and fall, when nights are cool and the ground stays wet. The University of Maryland Extension notes that slugs lay most of their eggs during those wetter months, and that every life stage can spend the winter in the soil. A rainy April or a wet September usually means more slugs on the porch and in the beds. In July and August heat, they go quiet and hide in damp spots under mulch, stones, and decks.

Our clay soils hold water, and many yards here have shaded beds that stay wet under thick mulch. That is good slug habitat. Slugs share it with earwigs, millipedes, and pillbugs, so if you lift a board and find one, you’ll often find the others too.

Slug Behavior and Biology

Each slug has both male and female parts, but two slugs still mate to make eggs. According to the University of Maryland Extension, a slug can lay up to 200 eggs, in small clusters about an inch deep in damp, loose soil or debris. The eggs are white or clear, round, and about the size of a BB. They hatch in about 30 days when the soil stays moist. Young slugs look like tiny adults and start feeding right away. They take 3 to 12 months to reach full size and can live for several years.

Slugs come out at night, on cloudy days, and after rain or watering. They spend the day under boards, mulch, rocks, and leaf litter, where it is cool and damp. They move slowly and leave a slime trail behind them.

Feeding Habits

Slugs have a rough, tongue-like mouthpart that scrapes food. They eat many plants, especially tender seedlings, lettuce, cabbage, strawberries, tomatoes, and hostas. They also eat fungi, rotting plants, and sometimes other slugs. A bad night in a seedling bed can wipe out most of the new plants.

Signs of Slug Activity

The clearest sign is the silvery slime trail on plants, soil, steps, and walls. Look for ragged holes in the middle of leaves, not just along the edges. Caterpillars leave droppings, and earwigs leave ragged holes too, but neither leaves slime. To be sure, go out after dark with a flashlight and look at the plants that are getting chewed.

Are Slugs Dangerous?

No. Slugs don’t bite or sting, and none of the slugs here are poisonous to touch. That includes black slugs, brown slugs, and leopard slugs. The real risk is a parasite. The CDC says people get rat lungworm by eating raw or undercooked snails or slugs, or raw produce like lettuce with a small slug, or part of one, on it. Most infections cause mild symptoms or none, but rare cases cause a type of meningitis. Wash garden produce well, wash your hands after handling slugs, and don’t let kids put them in their mouths.

How to Get Rid of Slugs

Better Termite does not treat slugs. They are a garden and moisture problem, and most of the fixes are things you can do yourself. Combining a few methods works better than any single one.

Dry Out Their Hiding Spots

• Water in the morning so the soil surface dries by evening.
• Pull mulch back a few inches from foundations and plant stems.
• Remove boards, bricks, leaf piles, and low weeds where slugs hide during the day.
• Thin dense plantings so air moves and sun reaches the soil.
• Fix downspouts and drainage that keep beds soggy.

Hand Picking and Traps

Go out after dark with a flashlight and drop slugs into soapy water. It works well for small problems and shows you where they gather.

For traps, bury a container with deep sides so the rim sits at ground level, and fill it with beer or a mix of water, sugar, and yeast. UC IPM notes these traps only draw slugs from a few feet away, so you need several, and you have to refill them every few days. A wet board or folded damp newspaper laid on the soil works too. Flip it in the morning and collect the slugs underneath.

Barriers

Copper: Copper bands keep slugs and snails from crossing. UC IPM recommends a band 4 to 6 inches wide around raised beds, with no gaps. Clean it with vinegar when it tarnishes. Pick out any slugs already inside the bed first.

Dry, rough borders: Slugs avoid dry, sharp surfaces. A border of gravel or coarse sand helps. Crushed eggshells give mixed results and stop working once they get wet.

Baits

Iron phosphate baits: These are the better choice for yards with pets and kids. UC IPM rates them far less harmful to children, pets, birds, and wildlife than metaldehyde. Slugs stop feeding after they eat it and die over the next few days. Scatter the pellets where you see the most slime trails.

Metaldehyde baits: These work, but UC IPM warns they are very poisonous to dogs and cats, and the pellets can attract dogs. If you have pets, skip them.

Natural Predators

Ground beetles, toads, turtles, snakes, and birds all eat slugs. Leave a little habitat for them and they will keep slug numbers down. Gardens with slugs often have other plant pests too, like aphids and thrips, which do well in the same damp, crowded beds.

Slugs Coming Inside

Slugs get indoors through gaps under doors, foundation cracks, and pet doors, usually after heavy rain. A slug in the basement means that space is damp. Seal the gaps, run a dehumidifier, and clear mulch and leaf piles away from the foundation. If the damp basement also has pillbugs, millipedes, or camel crickets, those are pests we do treat.

References

• Slugs and Snails on Vegetables - University of Maryland Extension
• Snails and Slugs Pest Note - UC Statewide IPM Program
• Slugs in Home Gardens - University of Minnesota Extension
• Slug Control - Pacific Northwest Pest Management Handbooks
• Snails and Slugs - University of Florida Gardening Solutions
• Limacus flavus (Yellow Slug) - Carnegie Museum of Natural History
• Philomycus carolinianus (Carolina Mantleslug) - Carnegie Museum of Natural History
• About Rat Lungworm Disease - CDC