White Slugs in Your Garden? Pros, Cons and How To Remove Them


What animal in your garden is not a worm, snail or insect, has a skirt, a foot, and 27,000 teeth? If you say it’s a slug, you’re absolutely right.

A white garden slug is a land mollusk found in gardens and fields. It contributes to natural ecosystems but can be a pest when it destroys plants and crops. Slug damage control includes DIY traps, no-kill, non-chemical kill, and chemical kill options.

Although they don’t sting, poison, or suck our blood, we often consider slugs as one of the most repulsive creatures in our garden. Perhaps it’s because they attack our plants quietly or because our fight-or-flight instinct is aroused by slimy creepy-crawlies.

In either case, this guide explains why garden slugs are good, bad, and what you can do about them.

What Are White Garden Slugs?

When the gray netted slug (Deroceras reticulatum) feels threatened, it covers itself in milky white mucus. That’s why it’s called a “white garden slug” even if it is also a gray field slug.

And that’s not all.

The D. reticulatum is the only slug in the USA that covers itself in white slime when scared. Only three other slugs in the world – out of its 80,000 land and water gastropods – secrete milky-white mucus when they’re disturbed:

The white garden slug is also often confused with the ghost slug (Selenochlamys ysbryda), the worm slug (Boettgerilla pallens), and the hedgehog slug (Arion intermedius).

PRO TIP: Most garden slugs are black, brown, yellow, speckled, or light gray.

More frequently, however, white garden slugs are confused with grubs or larva of insects such as June bugs, chafers, beetles, or billbugs.

People also confuse white garden slugs with some lighter examples of the round-back slug (Arionidae); the greenhouse slug (Milacidae); the meadow slug (Deroceras laeve); the tree slug (Lehmannia marginata); or the dusky slug (Arion subfuscus).

Identification

While it’s true that some of these land slugs are so alike and can only be distinguished when their digestive tract is dissected, there are simpler ways to identify a white garden slug:

  1. Common names: white garden slug, gray garden slug, gray field slug
  2. Body color: from cream to light gray
  3. Scientific name: Deroceras reticulatum
  4. Synonyms: Agriolimax reticulatus, Limax reticulatus, Limax tunicata
  5. Size: White garden slugs can grow up to 2 inches long (about 5 cm). Other slug species can grow up to 10″ long.
  6. Slime: Among the various Deroceras species in the USA, the D. reticulatum is the only that can change its clear body-cover mucus to milky-white when it’s irritated, harassed or disturbed.
  7. Color: The white garden slug has been seen in cream, greyish, beige, yellowish-brown, light pinkish gray, dark brown or other off-white colors, but most often with a pale body with a brownish mantle.
  8. Location: D. reticulatum has been observed in the following places:
    • USA: Alabama, California, Colorado, Hawaii, Illinois, Kentucky, Michigan, Ohio, Oklahoma, Utah, Washington, Wisconsin, Wyoming
    • Canada: Newfoundland, Quebec, Ontario, British Columbia
    • Asia: Sri Lanka
    • Australasia: New Zealand
    • Britain: Leicestershire, Rutland

RELATED LINK: Semi-Slugs – Real Monstrosities

FACTOID: It takes a group to do the wave in sports events, but slugs do it as a boring travel routine – and they do it alone.

Habitat

We’ve had D. reticulatum in the USA since 1843, but never in arid zones. They’re plentiful in lowland gardens, crop fields, parks, grassland, meadows, under rubbish and in arable fields. Slugs seem to prefer synanthropic, disturbed soils on roadsides and in greenhouses.

At the same time, white garden slugs can survive in light soil with irrigation, but not in finely tilled or compacted soil. They prefer moisture-retaining soil (such as clay) with a lot of organic matter (such as compost or manure) where they can hide.

Most of all, D. reticulatum flourishes in no-till fields, gardens with moist, cool, heavy, slightly alkaline to neutral soil and lots of crevices, cracked soil, rubbish, pots, logs, and other hiding places, but not in sandy soil that quickly dries out and offer few hidey holes.

USEFUL LINK: Interactive map of slug habitats around the world

FACTOID: Like humans, female slugs live longer than male slugs.

Appearance

Slugs are the shell-less versions of their cousins in the Gastropod (stomach-foot) Family: think of soft-bodied snails, clams, mussels. And, yes, they use one foot under their bellies to move around.

Why is this relevant?

As we all know, the first step to managing a problem is to know all that you can about it. For instance, think about how water and moisture are critical to a slug’s survival:

  • A slug has a soft and elongated body that is 80% water and collagen that envelopes its blood vessels, and its granular, pigment and vesicular cells. It can survive even after losing 50% of its body mass. Your strategy: Remove moisture from the garden.
  • A slug doesn’t have a shell or a plate, so its body surface is covered with slime to avoid desiccation. When its skin dries out, it can directly absorb any available water through its skin. Your strategy: Remove moist hiding-places in the garden.

The more you know, the better your strategy, so here’s a quick review of slug anatomy.

  1. Head: The slug’s head includes a radula (mouth) as well as upper and lower tentacles. Six connected ganglions (a group of neurons) in the head serves as a brain.

FACTOID: A slug’s brain has a circadian clock that recognizes night from day.

  1. Mouth: The slug’s mouth (radula) is smaller than a pinhead but contains a ribbon-like tongue with 27,000 teeth.
  2. Upper tentacles: There are two retractable tentacles that can detect odors and light. The eye spots at the tips can’t form images but detect light and darkness. Lost or damaged tentacles can grow back.
  3. Lower tentacles: There are two lower tentacles for tasting and for touching. The upper and lower tentacles are independent.
  4. Slime (mucus): D. reticulatum covers its body in transparent slime to stay hydrated, prevent infection, promote healing, and protect itself with white mucus when disturbed or threatened.
    • Slugs produce a trail of lubricant slime to glide on rough surfaces. It’s a sticky glue for vertical travel and protects its foot from injury, bacteria, and fungi.
    • Slug slime is neither solid nor liquid. It’s a crystal gel containing salts, proteins, carbohydrates, and water. It is elastic, adhesive, lubricating, and hygroscopic, absorbing water from the air up to 100 times its weight.
    • Slugs examine slime trails to find potential mates and learn about each other.
  1. Pneumostome: This is a respiratory pore on the right side of the slug’s mantle and it’s connected to the lung. However, a slug can also breathe through its skin to absorb oxygen directly from the air.
  2. Mantle cavity: Behind the slug’s head is a fleshy lobe with a cavity containing the genitals, anus, and lung.
  3. Gonopore: Under the slug’s mantle cavity is the gonopore, a hole where eggs and sperm are released.
  4. Skirt: Right above the slug’s foot is a skirt used for navigation.
  5. Foot: At the bottom of the skirt is a foot with a sole in 3 parts.
  6. Pedal gland: The foot’s pedal gland secretes mucus.
  7. Keel: The keel is a ridge that runs from behind the mantle, along the middle of the tail, down to the tail end.
  8. Tail: Behind the slug’s mantle is a rounded tail with a tip that can be self-amputated for escape. Autotomy is unique to tail-dropping slugs.

FREE PDF: Managing Slugs in the Garden and Beyond (8 pages)

FACTOID: When a slug has to enter tiny spaces, it can flatten and elongate its body 20 times its normal length.

Reproduction

If you’re concerned about a slug infestation in your garden, then you should know how they multiply and how to find their nest eggs. Here’s a summary of what we know.

  1. Reproductive organs: Like all snails, land slugs are true hermaphrodites. Every adult slug has male and female reproductive organs.

FACTOID: Slug penises are at least half their body length.

  1. Mating: Most slugs mate at ground level.
    • First, a slug drops a chemical (some species shoot love darts) on its slime trail to indicate readiness to mate.
    • Foreplay takes hours.
    • One may be inseminated or there is reciprocal insemination.
    • When sex organs get stuck, one apophallates the other so that they can separate.
    • The dismembered mate lives on as a female.
  1. Fertilization: Inseminated slugs don’t fertilize right away.
    • They store the sperm until conditions are right for hatching.
    • In tough situations, some slugs can self-fertilize.
  2. Eggs and nests: Garden slugs can lay from 12 to 40 gelatinous, watery eggs per batch (average: about 40 eggs per cluster).
    • These eggs can be found in soil cracks, under logs, stones, pots, bricks, pieces of wood, or logs.
    • The 4-millimeter eggs are round or oval, generally pearl-like, translucent when young, and yellowish-white later.
    • The eggs remain dormant up to several years, waiting for the right hatching environment.
    • Eggs laid in late winter can take from 2 to 5 months to hatch while eggs laid late in October hatch next spring.
  1. Development: Neonates: The neonate or newly-hatched slug weighs from 1 to 10 mg.
    • Baby slugs can feed on plants but prefer algae and fungus.
    • Neonates don’t go far from their homes. Even later as adults, slugs have a homing instinct that they follow automatically.
  2. Juveniles: Juvenile slugs weigh between 11 and 110 mg.
    • Most juveniles begin feeding and grow through the spring or in the summer.
    • When times are really tough, they estivate and conserve their energy to survive drought, or intense heat. They can survive without food for months.

PRO TIP: Slugs that are picked up and thrown away can return home by using their natural homing instinct.

  1. Reproductive frequency: Between 3 to 12 months, juveniles become adults. In temperate zones, they mature in late summer or early fall.
    • Mating and laying eggs happen anytime, but mostly in the fall.
    • In temperate zones, a slug can produce two generations per year: one in the early spring, and another in the fall.
    • A slug can lay at least 500 eggs in 24 months.
    • Some slug species can produce up to 90,000 babies before they die

PRO TIP: Some slug species that live up to 7 years take about 2 years to mature.

FREE PDF: Managing Slugs, Snails, and Flatworms in the Home Garden (4 pages)

Activity Patterns

If you want to catch slugs in the act of destroying your plants, then you should know when and where they hide and feed.

It’s easy to observe them because they’re pretty laid back. In fact, it takes them a week to travel one mile. One gardener took time and found that they can travel more than 20 yards a day. Research tells us even more.

  1. Coming out: Adult garden slugs come out at dusk and are active all night. D. reticulatum is most active between four to six hours after dark and between 3 A.M. or 4 A.M.
    • At sunrise, they hide in the soil where it is moist and cool. Sometimes, they come out on foggy, overcast, or cloudy days.
    • They’re very active outside when days are damp and the air is cool, particularly from April to June and from September to October.
    • They’re still active when temperatures are just above freezing.
  1. Walking: A slug’s foot is its biggest muscle, making up most of its body mass. To creep, a slug contracts foot muscles to make a wave from back to front. This shear stress technique is called adhesive locomotion:

o The slug uses slime to stick one part of its body to a surface.

o It uses its muscles to move the free body parts forward.

o While the forward parts are adhering to new slime, the slug pulls away its other body parts from the slime.

o The slug then releases more slime and repeats the process

  1. Feeding: Slime trails in the early mornings show that slugs are feeding at night.
    • Each night, slugs can eat up to 2x their body weight.
    • Most slugs feed above the soil, particularly on young plants with leaves closer to the soil.
    • Generalist garden slugs eat anything: they are herbivorous, carnivorous, omnivorous, and detritivores (decayed waste eaters), herbivores (plant eaters), carnivores (animal eaters), and omnivores (eats any organics).
    • Specialist slugs eat worms, vegetation, rotting vegetation, animal waste, fungi (mushrooms), and small invertebrates.
  2. Feed points: Slugs feed during different stages of the life cycle of plants:
    • The seed stage (wheat, small grains)
    • The seedling stage (vegetables)
    • Just before stems shoot out of the soil (green asparagus)
    • From tuber formation to harvest stage (potato)
    • The fruit ripening stage (strawberries)
    • The pre-harvest stage (most vegetables)

FREE PDF: Slugs and Snails in Oregon (42 pages)

FACTOID: The native Banana Slug is the biggest slug in the USA that grows up to almost a foot long.

1. What’s Good About White Garden Slugs?

Generally, slugs are harmless, quiet, and unobtrusive. Of the more than 80,000 gastropods on earth, only a few are considered as garden pests. In fact, most garden slugs are crucial to the health of garden soil and plant ecosystems.

And they’re much smarter than we thought.

For instance, computational neurobiologist Alan Gerpelin of Lucent Technologies says that slugs can, in some ways, match how rats, pigeons, or humans learn. After more than 20 years of study, he saw how slugs learn pattern recognition better than computers can.

In fact, he says, they weigh evidence and make decisions about the same things that concern us: choosing nutritious food, mating with a good partner, avoiding injury and death.

But that’s not all. Slugs actually benefit mankind in practical ways. Here’s how D. reticulatum helps mankind in some research areas:

  1. Neuroscience: Slugs make great experimental subjects because their simple nervous systems can be studied even without a microscope.
  2. Neurobiology: Neurobiologists learn from the slug brain, which has large neurons that function even after removal from the brain.

FACTOID: The slug brain has about 220,000 neurons compared to the human brain’s 10 billion.

  1. Bacteriology: Scientists around the world have studied the use of slug slime for diagnosis of bacterial infections, cell-to-cell communication, anti-viral molecules, as well as the antimicrobial and anti-bacterial properties of slug mucus.

RELATED RESEARCH: Antimicrobial properties of terrestrial snail and slug mucus.

  1. Agriculture, Horticulture: Slugs consume and compost vast quantities – more than their body mass, in fact – of dung, decaying vegetation, carrion, and other organic matter.
    • Slugs help maintain a healthy soil ecosystem by eating and turning into soil centipedes, beetles, earthworms, plant materials, lichen, fungi, and carrion.
    • The importance of garden slugs is confirmed worldwide by researchers in countries such as Latvia, Canada, and the USA to mention a few.
  2. Medicine: Since ancient times, traditional and folk medicine used snail as emollients, for skin inflammations, wounds, burns, abscesses, nosebleeds, nephritis, tuberculosis, and hydrops fetalis.
    • The medical applications of slug mucus includes parasitology, toxicology, genetics, and surgery.
  • Slug mucine contains a glycoprotein rich in glycolic acid (collagen synthesis, minimizes wrinkles), allantoin (healing the skin), elastin, and osteopontin as well as natural peptides that are useful for dermatological, pharmacologic and therapeutic applications.
  • Slug slime can be used as an antiviral agent against the measles virus (Morbillivirus) and as an antimicrobial agent against MRSA (methicillin-resistant Staph. aureus).

RELATED VIDEO: Have You Tried ‘Slugging?’ Meet The Slimy New Korean Beauty Trend (2:29 minutes)

Now that we know some of the good stuff that slugs do for us, why are there so many anti-slug folks? What’s so bad about garden slugs? Read on!

2. What’s So Bad About White Garden Slugs?

Few people know that most slugs eat decaying organic matter. The fact is, only a few species of slugs eat living plants. Still, when slugs destroy crops and gardens, we hate it more than the slimy mucus.

Did you know how difficult it is to remove fresh slug slime from hands and clothes?

a. Slimy Mucus

As mentioned, the white garden slug uses up to about one-third of its total energy budget to produce viscoelastic slime. There are three types of slug slime:

  1. Hydration: This is a thin, watery, and clear slime that oozes out of their skin to keep them hydrated and – just as important – tastes yucky to predators.
  2. Travel: A gland on the slug’s foot produces a thick, sticky mucus that contains an adhesive that allows the slug to glide over rough or sharp surfaces, as well as move on vertical surfaces in any direction.

Defence: This is a milky-white slime that covers the entire body when the D. reticulatum feels irritated, disturbed, or frightened. It contains an adhesive that can gum up the mouths of most predators.

Since slugs eat decaying bio-organisms including waste and carrion, their slime may contain parasites that are harmful to humans. When you get slimed, you want to wash it off fast.

But, wait! Actually, that’s not the best thing to do.

  1. Do not wash: Do not use soap and water because the slime will be very sticky and almost impossible to remove.
  2. Let dry: First, wait a few minutes until the mucus dries.
  3. Rub dry: Rub your hands together until the slime forms into balls. Remove it as you would remove rubber cement.
  4. Borax powder: You can also rub your dry hands with dry powdered borax hand soap. The powder will form the slime into small balls that will fall off. Repeat as necessary, then wash your hands.
  5. Salt and flour: No borax soap? Mix equal parts of salt and flour, rub it into your hands or skin, then pick off the slime like picking off school glue. Repeat as necessary.
  6. Use salt: Pour a generous amount of salt into your palm and rub your hands together briskly for a few minutes, particularly on the slimy parts. Let the dried mucus roll off. Rinse afterwards with soap and water.

If slime gets on fabrics such as clothes, curtains, blankets, towels, or rugs, let the slime dry before doing anything.

  1. Baking soda: Apply baking soda on the fabric. Let it seep for about 10 minutes, then scrub vigorously in water with a washcloth or brush.
  2. Vinegar: Soak the area with vinegar for about 10 minutes, then scrub with soap and water.

If slime gets on other surfaces such as floors, furniture, etc., rub the area dry with a paper towel. If that does not work, cover the area with baking soda for about 10 minutes. Then, scrub dry, sweep, and wash the floor.

b. Feeding Damage

A high population of slugs can completely defoliate entire crops, even tobacco fields.

For instance, The Willamette Valley suffered more than $60 million of slug damage in 2012. However, more frequent, more severe slug damage continues to happen in France, the Netherlands, Great Britain, and Ireland, to mention a few.

Slugs kill plants when they feed on the apical meristem or growing point. When they feed on fruits and vegetables, fungi and bacteria infect and destroy the leftovers and initiate rotting or mold growth.

In short, they’re serious pests.

Unless they’re controlled, slugs can cost farmers and gardeners up to US $133,670,000 (£100 million), says an HGCA report. Each year, slugs destroy 53,280 tons of wheat, only 1.1 percent of the total crop volume but worth at least US $34,000,000 (£25.5 million).

In gardens and farms around the world, D. reticulatum seems to be the most damaging of all slug species, particularly on Fabaceae (legumes, peas, beans), Brassicaceae (mustard, cabbage), Asteraceae (artichoke, lettuce, endive), and cultivated cereals.

Slugs prefer soft, thin, tender leaves containing starch (yeast) and sugars, particularly young shoots, seedlings, and plantlets. To combat the damage, you can use slug-resistant plants or you can use trap crops.

c. Slug-Resistant Plants

You can choose slug-resistant plants for your garden, such as bamboo, wintergreen, candytuft, agapanthus, yew, anemone, sweet woodruff, astilbe, solomon’s seal, bleeding hearts, sedum, impatiens, nandina, coral bells, juniper, ferns, foxglove, ivy, hens and chicks.

RELATED VIDEO: What plants deter slugs in the garden? (4:44 minutes)

FREE PDF: Cool Facts – Slugs (2 pages)

RELATED VIDEO: Organic Slug & Snail Control for Vegetable Gardens (10:43 minutes)

d. Slug Trap Crops

You can protect important plants by diverting slugs towards plants they particularly like. For instance, many organic gardeners use red clover (Trifolium pratense) and chervil (Anthriscus cerefolium) as trap plants.

At the same time, keep in mind that you must position the trap crop far away from the plants that you want to protect for slugs.

For instance, you want to protect herbs, fruits, and vegetables that are highly conducive to slug feeding such as basil, beans, corn, strawberries, cabbages, celery, broccoli, lettuce (crisphead, Boston except tough romaine leaves), red clover, soybeans mustard, wild ginger, and small grains such as barley and corn, and potato (some varieties resist slugs).

Some slug trap plants that you can use are begonias, cannas, chervils, coleus, dahlias, delphiniums, hostas (thin-leaf types), impatiens, begonias, Japanese painted ferns, leopard’s bane, marigolds, campanulas, daffodils, gentians, lobelias (perennial), marigolds, primroses, stars of Bethlehem, trilliums, tuberoses, and violas.

PRO TIP: Insect and slug feeding look exactly the same, except for one tell – silvery mucus trails.

RELATED LINK: Trap plants for slugs

FACTOID: Research shows that, in the UK, there are at least 200 slugs in a one-cubic meter garden, and at least 250.000 slugs in an acre of farmland.

3. How To Get Rid Of White Slugs?

When slugs feed, they don’t know they’re killing plants or destroying crops. But when they do, you have options including non-killing, DIY traps, chemical and non-chemical killing. All are labor-intensive, and none are perfect.

a. No-Kill Options

Killing off snails and slugs doesn’t work. Research indicates that casual killing removes only a tiny part of a large population, so your garden gets little benefits despite your best efforts. Besides, slugs do your garden a lot more good alive than dead.

RELATED LINK: Why you should not kill snails or slugs

Here are some humane and eco-friendly methods that are safe for children, pets, and wildlife.

  1. Wipe trails away: Slugs follow the trails of other slugs.
    • Observe slime trails to see where slugs travel at night.
    • Wipe away slime trails that lead to your garden.
  2. Reduce humidity: A university report says that reducing humidity can reduce slug damage in your garden by as much as 80%. Effects may not be immediate.
    • Change your watering schedule to early mornings instead of late afternoon or evenings. This way, soil and leaves will dry before slugs come out at night.
    • Limit water and decrease humidity around plants with soaker lines or drip irrigation.
    • Wider plant spacing and trellises increase air movement and reduce high moisture around plants.
  3. Remove hideaways: Remove damp, dark hiding places.
    • Rake garden soil.
    • Turn over debris, mulch, and so on.
    • Remove fallen leaves
    • Avoid organic mulches such as grass clippings or straw.
  4. Trap and move: Lay wet cardboard, old newspaper, or boards on the soil near plants being attacked by slugs.
    • Check every few days and for slugs hiding underneath.
    • Look closely. Juvenile slugs are very small; neonates are even smaller.
  5. Bait and move: Place orange or citrus rinds on the ground to bait slugs away from plants.
    • Remove snails or slugs every morning.
    • Refresh your decoys as necessary.

PRO TIP: Cut openings along the rims of a tin foil plate. Moisten with some water and place upside-down on some pet food. Check during the day and remove slugs.

  1. Collect and move: An hour or two after sundown, take a flashlight and collect slugs and snails (wear gloves, use tongs, tweezers, or chopsticks). Move them at least 20 feet (6.1 meters) away to confuse their homing instinct.

RELATED RESEARCH; Olfactory Basis of Homing Behavior in the Giant Garden Slug (5 pages)

  1. Rough surfaces: Slugs avoid acid, abrasive, or alkali surfaces. Only starving slugs will try and cross these. Surround the stems of plants with 1-inch-high, 3-inches wide rough, dry surfaces such as sandpaper, coffee grounds, crushed eggshells (careful: this can raise soil pH), sand, sawdust, hair (this adds nitrogen to soil), coffee grounds, salted nut shells, ash, lime, or diatomaceous earth (food grade only).

PRO TIP: These do not work when wet.

  1. Electric shock: Wrap a wide enough layer of copper tape, mesh, wire, band, or foil around trunks or plant containers.
    • Glue pennies around the tops of plant containers.
    • Surround your raised beds and greenhouse benches with copper flashing.
    • Use copper plant guards or a Slugs Away fence. When slimed, these create a mild, non-lethal electric shock that also keeps mice away.

PRO TIP: Copper strips sold in garden shops may not be wide enough.

  1. Plant herbs: Slugs don’t like herbs such as sage (Salvia officinalis), mint, hyssop, chives, garlic, fennel, geraniums, and foxgloves. (They also hate rhubarb leaves, but keep in mind that this plant is toxic to humans and pets.)

PRO TIP: Do not be confused and plant tropical sage or scarlet sage (Salvia splendens), which attracts slugs.

  1. Pine seed extract spray: A high dilution of 3 parts pine seed extract to 1000 parts water is a non-lethal solution that will keep slugs away from your plants. Spray regularly as this doesn’t work when it evaporates or dries.
  2. Coffee spray: Brew a strong batch of coffee (black, no sugar) and let it cool.
    • Spray undiluted under leaves, on stems, and on the soil around plants at night.
    • Re-spray as necessary.
    • Too much caffeine can harm plants.

PRO TIP: Research shows it’s effective, but sometimes it doesn’t work.

FREE PDF: Non-Chemical Snail & Slug Control (2 pages)

RELATED LINK: Slug Predators – Identify and Attract Natural Enemies of Slugs and Snails to Your Garden

b. DIY Traps

If you have a small garden, finding slugs among your plants may not inspire you to go out and buy something. Here are some traps that you can make out of household ingredients and materials.

Note that these have no scientific proof, and that they don’t always work for one reason or another. Choose and test to see what works best for you.

  1. Beer: It’s the smell of yeast that attracts slugs to beer. You may also add some dissolved sugar, honey or molasses (Hint: Yeast and sugar are also found in plant leaves, fruits, flowers, and soda).
    • Rinse an empty milk carton, plastic container or jar with cover with water. No need to use soap or to dry it.
    • Punch some holes on the sides near the rim or on the cover (or you can buy a beer trap).
    • Fill it with 2 inches (or more) of beer. Don’t use stale beer (you can also ask a local beer distributor for overruns).
    • Near your vulnerable plants, dig a hole in the ground, just enough to fit the container.
    • Cover loosely with soil (don’t pack the soil) and mark the spot with some upright sticks for later retrieval.
    • Change the beer every 24 hours.

FACTOID: Slugs are not attracted to alcohol.

  1. Boards or planks: Lay some moist, old planks, boards, and so on between your plants or garden beds.
    • In the morning, lift the boards.
    • Scrape the slugs into a bucket.
    • You can freeze them to death before disposal or adding them to compost.
  2. Fruit hotels: Hollow out some grapefruit, lemon, melon or orange halves (rinds and skins work too).
    • Leave them overnight, face down on the ground (like dome tents).
    • Collect them first thing in the morning.
  3. Trap crops: Trap crops, or sacrificial crops, are planted to diver slugs away from the plants that you want to protect.
  4. Wet Newspaper: Wet any paper thick enough to keep out the sun: folded newspaper, cardboard, old mail, and so on. Early evening, place these on the ground. Slugs will seek out the dampness and shelter.
  5. Yeast: If you don’t have beer, use the following recipes:
    • Dissolve 1 tablespoon of baker’s yeast and half a teaspoon sugar in 1 cup of lukewarm water.
    • Dissolve 1 tablespoon of flour, half a teaspoon baker’s yeast, and half a teaspoon sugar in 1 cup of warm water.

FREE PDF: Organic solutions for slugs and snails (3 pages)

c. Nonchemical Kill Options

If you don’t care about protecting slugs’ right to live but you care enough to avoid using toxic chemicals, you can kill slugs with salted or boiling water, cut them with a sharp edge, salt them, or drown them in soapy water.

If that doesn’t work for you, here are some other options.

  1. Frogs, toads: Encourage toads, frogs, salamanders, newts to live in your garden with water low in the ground and a damp shady spot. They eat lots of slugs.
  2. Glow worms: Encourage lightning bugs to lay eggs in your garden: Do not use lawn chemicals, turn off outdoor lights at night, and leave a part of your garden moist and weedy for them. Their larvas (Lampyridae) eat lots of slugs and slug eggs.
  3. Nematodes: The British company Nemaslug sells microscopic Phasmarhabditis hermaphrodita (Rhabditidae), a dauer-larva nematode or eelworm that kills slugs and their eggs in 3 days.
    • It is sold in 15 countries including the UK, the Netherlands, the Czech Republic, Denmark, Belgium, Finland, Germany, France, Ireland, Norway, Italy, Poland, Sweden, Spain, and Switzerland.
    • It is easy to use but has a short shelf life (4 weeks from manufacture).
    • It needs to be reapplied every 6 weeks.
    • It may be too expensive for regular use in large crop fields.
    • Despite successful efficacy tests in the USA and discovered in New Zealand and in western United States, this biocontrol product is prohibited by statutory regulation and is not commercially available in these two countries.
  1. Pots & Cloches: Grow plants in pots, containers, or tubs. To prevent snails and slugs from climbing in, spray waterproof WD-40 around each plant container. You can add more plant protection by using cloches.

RELATED VIDEO: How to make a homemade plant cloche (0:55 seconds)

  1. Rove beetles: Rove beetles (Staphylinidae) eat lots of slugs and slug eggs. Don’t touch – they excrete pederin that causes skin blisters.
    • Insects such as harvestmen (Opiliones), wolf spiders (Lycosidae), and centipedes (Chilopoda), snakes, millipedes, and marsh flies (Sciomyzidae) also eat slugs.
    • At the same time, many agree that ground beetles (Carabidae) are most effective against garden or field slugs.
  2. Scorched earth: The ‘scorched earth strategy’ is a historically proven military strategy where you destroy anything that the enemy can use:
    • Get rid of ground cover:
    • Remove debris, dead wood, and rocks.
    • Cut away vegetation.
    • Raise garden items off the ground.
    • In storage sheds, arrange pots and tools on blocks, not on the ground.
    • Till or turn over topsoil to evaporate moisture.
    • Don’t irrigate or water your plants in the afternoon or evening.
  3. Spear: In the evening, use a flashlight and a long, sharp stick to impale slugs.
  4. Till and peck: Till or turn over the soil with a hoe or shovel, and release ducks or chickens who will eat all the slugs they see. You can use the eggs too.

d. Chemical Kill Options

Molluscicides to kill slugs and snails use chemicals different from those used against garden pests and insects. Most molluscicides use ferric phosphate or metaldehyde. The following table summarizes the various options.

  1. Ammonia Spray: Mix 50% ammonia and 50% water and spray directly on slugs or slug eggs.
  2. Ferric phosphate pellets: Iron phosphate is a pesticide that is used as a human mineral supplement. Slugs eat iron phosphate pellets containing pesticide.
  1. Garlic spray: Peel and crush fresh garlic, soak in water, and spray undiluted on your plants after sundown. Note: This is lethal to slugs and snails.
  2. Metaldehyde pellets: Metaldehyde is a chemical commonly used against slugs. However, this chemical is highly toxic to humans, pets, and wildlife.
  3. Methiocarb pellets: Slug pellets may contain methiocarb, a non-selective carbamate chemical. It is a stomach poison that is toxic to pets, birds, and other animals.
  4. Nitrogen spray: Use a 30% urea-based nitrogen solution mixed with the same amount of water.
  • Apply 20 gallons per acre.
  • Repeat a few nights in a row for best results.
  1. Salt, Epsom: Epsom salts (magnesium sulfate on Amazon) deter slugs and snails when sprinkled on the soil. It also prevents magnesium deficiency in plants.

PRO TIP: A single grain of salt is lethal on a slug.

  1. Vinegar spray: Mix 1 cup kitchen vinegar and 1/2 cup water.
  • Spray the ground at night.
  • Do not spray plant leaves (can damage).

PRO TIP: Slugs cannot be poisoned by using most insecticides.

FREE PDF: Snail and Slug Management for Home Gardeners and Landscape Professionals (6 pages)

4. Common FAQs & Answers

Here are some of the most common questions about white garden slugs.

Question: Is slug slime harmful to humans?

Answer: Slug slime itself is harmless but some slugs and snails may be infected by parasites such as the rat lungworm (Angiostrongylus costaricensis).

Question: Why do I rarely see slugs in my garden?

Answer: You won’t see them unless it’s early morning or early evening. They feed when it’s dark and cool and hide during bright, dry days.

Question: Do slugs feel pain?

Answer: According to Alice at Warwick, the answer is no.

Question: Can we eat slugs?

Answer: They’re considered as delicacies in some cultures. You can eat fried slugs in egg and breadcrumbs, or in tomato sauce, but remove the mucus first, as that can be bitter. Black slugs may taste like rubber tires, although some slugs have no taste. Remember that a slug should be cooked thoroughly before you eat it so as to avoid parasitic nematode infection.

FREE PDF: Snail And Slug Ingestion by Children: Practice Guidelines (5 pages)

RELATED LINK: Why You Shouldn’t Eat a Slug (In Case You Need Reasons)

5. Takeaways

Now that you’ve reviewed what we know about white garden slugs, let’s wind up with a few takeaways you can easily remember.

  • Field or garden slugs that appear white may be covered in white slime because they’re disturbed.
  • Slugs contribute a lot to research, ecology, therapy, and medicine. At the same time, they can also destroy plants and can even entire crops.
  • If slugs have no access to fruits or vegetables, they will eat almost anything else so they won’t starve or die of hunger.
  • There’s no comprehensive, thoroughly effective ways to keep slugs away. However, there’s a lot of options that don’t involve killing, spending money, or using toxic chemicals. Choose what works best for you.

And there you have it.

Congratulations! You’ve just read the most comprehensive guide ever on white garden slugs.

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Andrea

A young Italian guy with a passion for growing edible herbs. After moving to the UK 6 years ago in a tiny flat, it was impossible to grow herbs outside. So I start my journey in growing indoor and so I decided to share my knowledge.

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