You may have spotted these pesky creatures in your yard, or you’ve noticed the trail of slime and destruction that they leave behind after ravaging your plants and seedlings overnight.
Even though a small number of slugs can play a beneficial role in the ecosystem of your backyard, they can quickly multiply and take over, feasting on your crops and destroying your garden plants.
There are a number of ways to get rid of slugs naturally, including manual removal by hand, setting up beer or fruit traps, and killing them using salt or an alcohol spray. You could also use an organic pesticide or as a very last resort, a chemical pesticide. You can also take some preventative measures to stop them from returning; removing garden debris, only watering when necessary, and encouraging the presence of natural slug predators in your yard.
This article explains how to identify common slug species, the types of plants that slugs are attracted to and repelled by, the telltale signs of slug damage in your yard, and several methods you can use to get rid of slugs and keep them away from your precious garden crops for good.
What Are Slugs?
Slugs are a common garden pest found throughout most parts of the world, being most prevalent in areas with warmer, humid climates. They aren’t insects, but are instead classed as soft-bodied mollusks, being in the same category as octopuses and oysters. They move around by sliding on one muscular foot, devouring plant matter and leaving behind a trail of slimy mucus.
Slugs are essentially snails without external shells. However, some species of slugs have internal shells or have a prominent mantle running along their back.
They have four tentacles that protrude from their head; the upper two tentacles have eyes on the tips, being responsible for the slug’s sense of sight and smell; the shorter, lower two tentacles enable them to touch and taste things.
How to Identify Slug Species
The majority of slugs have either gray, light-yellow to light-orange, to dark brown bodies, and are about 1 to 3 inches in length. Refer to the table below for more specific identifiable features of some of the most common types of garden slug.
|Slug Species||Identifiable Features|
|California Banana Slug||Bright yellow with black spots, appears similar to a banana|
|Carolina Mantleslug||Covered in a mottle of black speckles, has mantle running from head to tail|
|Changeable Mantleslug||Light brown with brown flecks|
|Dusky Slug||Light brown to yellow in color, small in size|
|Leopard Slug (or Great Gray Slug)||Light brown with dark brown flecks, appears similar to leopard print|
|Pacific Banana Slug||Yellow and may have mottle of dark brown speckles or patches, can grow up to 10 inches long|
|Reticulate Taildropper||Light brown to red, has mantle section near head|
|Scarletback Taildropper||Red back with gray sides, can grow up to 2 inches long|
|Striped Greenhouse Slug||Light brown, can grow up to 3 inches long|
|Three-Banded Garden Slug||Pale brown with three dark brown bands running lengthwise on body|
|Winding Mantleslug||Light brown with mottle of dark brown flecks, less than 1-inch long|
|Yellow-Bordered Taildropper||Yellow to light brown, dark diamond-shaped mesh pattern on tail|
What Attracts Slugs to a Lawn or Garden?
Wet or Damp Soil
Slugs are primarily attracted to areas with wet or damp soil. They are extremely prone to becoming dehydrated, so areas of your yard with wet soil provide slugs with the ideal conditions to retain moisture in their bodies.
Overwatering your lawn or garden to the point that the soil is overly damp throughout the day increases the chances of a slug infestation. This is particularly if your yard contains a soil type that doesn’t drain well, such as clay-heavy soil.
Stones, Wooden Logs, and Piles of Dead Leaves
Slugs tend to gravitate towards dark, sheltered areas, for instance underneath large stones, wooden logs, or piles of dead leaves. Objects like these provide slugs with protection from the sun and wind which would otherwise dry them out. They especially rely on these spots in the summertime when they need somewhere to stay cool and moist.
Tall Grasses and Overgrown Shrubs
Tall grasses and shrubs also provide shelter for slugs. If you fall behind on your regular mowing schedule, or fail to remove unwanted vegetation like wild shrubs or bushes, this could increase the number of slugs finding their way into your yard.
Slugs are more attracted to yards with plants that have fleshy foliage and stems. This is why they are often found feasting on plants such as lettuces, cauliflowers, and marigolds. See the following section for a more extensive list of the plants and edibles that slugs are most attracted to.
What Do Slugs Eat?
Although they are infamous for destroying garden crops, slugs have evolved to eat pretty much every type of organic matter; they are categorized as herbivorous, carnivorous, omnivorous, and detritivorous (meaning that they eat the decayed waste of other animals and plants). Their diet varies from species to species, with there being specialist and generalist types of slugs that eat anything from vegetation, rotten vegetation, fungus, animal waste, worms, and even other slugs.
In terms of garden plants, they will usually opt for flowers or vegetables which have fleshier foliage and stems.
Plants that slugs are most attracted to include:
- Sweet Peas
Edibles that slugs are most attracted to include:
- Brussels Sprouts
- Dwarf Bean
- Runner Bean
What Plants Do Slugs Hate?
There are a few plants that slugs will avoid, despite their nature to devour most organic materials. They tend to steer clear of plants with a strong or unpleasant odor, or those that taste bitter to them. They also avoid plants that have tough, waxy, or hairy leaves, or shrubs with hard stems, as these are more difficult for the slugs to chew on.
Plants that slugs avoid include:
- Jacob’s Ladder
- Lamb’s Ears
- Lenten Rose
- London Pride
- Tree Peony
Edibles that slugs avoid include:
- Red Cabbage
- Red Lettuce
What Are the Signs of Slug Damage in a Garden?
Slugs feed on both living and decomposed plant matter, but they are most fond of young plants in the early stages of growth. They are renowned for decimating the tender stems and leaves of seedlings, but are also capable of doing some real damage to mature plants, fruits, and vegetables.
There are several common tell-tale signs that you’re dealing with a slug infestation in your yard:
Young, tender plants are a slug’s favorite food. If you go into your garden in the morning and notice that any growing seedlings have been reduced to their leaf mid-ribs and stumps, this is a sign that there has been slug activity overnight.
Damage on Leaves or Edibles
After feeding on your plants, slugs will leave behind a distinctive pattern of damage from their bites. Noticing ragged or scalloped holes on the centers and edges of leaves, or perfect, circular holes on soft fruits or vegetables, is clear evidence that the damage has been caused by slugs. They will often leave stem pieces untouched.
Timing of Plant Damage
Slugs are most active in early spring when many other populations of garden pests are still inactive. For this reason, damage that occurs during this time is most likely caused by them. In terms of the time of day, slugs do their worst damage overnight, and this damage is often exacerbated after periods of heavy rain.
Trail of Slime on Plants or Outdoor Surfaces
Slugs leave behind a trail of silvery-looking slime wherever they have been. You will be able to see this slime on the chewed leaves of your plants, or along walls, pavements, rocks, wood, or mulch in your yard.
Are Slugs Beneficial for a Garden?
In small numbers, slugs can actually be quite beneficial for your lawn or garden. In a similar fashion to vermicomposting (worm composting), slugs will enrich soil with their waste; as they eat organic matter, it breaks down in their bodies, then they release their nitrogen-rich castings, thus giving the nearby soil a boost in this primary nutrient needed by plants to grow.
They are also good for homeowners who are lovers of wildlife; they are a food source for many of their natural predators, such as birds, frogs, toads, snakes, and lawn-friendly insects.
How to Repel Slugs
Create a Repellant Barrier of Sharp or Drying Materials
Slugs will be thwarted by a barrier of sharp or drying materials. These pests have soft bodies that are easily irritated by coming into contact with materials such as these, meaning they will avoid traveling over any bumpy or drying materials, preventing them from reaching any plants within.
Place a barrier of your chosen material around individual plants that you would like to protect, or around the perimeter of the whole garden. There is a range of materials you could use for this method, including diatomaceous earth, gravel, lava rock, sand, wood ashes, crushed eggshells, pine needles, wool pellets, and dried granulated seaweed.
Take note that if you use wood ash for this method, it will add potassium to your soil, as well as raising the soil pH. If you use sand, this will have the added benefit of helping the soil to retain moisture.
Create a Repellant Barrier of Copper
Placing a barrier of copper around your garden can help to repel slugs. It is claimed that whenever these pests come into contact with copper, their slime reacts with the metal and gives the slug an electrical shock, which makes them retreat back to where they came from.
While this shock isn’t enough to kill the slugs, it will prevent them from entering your garden and discourage them from attempting to return.
Place a barrier of 4- to 6-inch copper flashing around areas that contain slug-attracting plants, or you could alternatively wrap these plants in copper tape. For raised beds, try creating a collar of copper by stapling or nailing a strip of copper tape around the outer edge of the bed on top of the bed’s frame.
This same method can be used on containers onto which the copper tape can be placed inside the pot’s upper rim. You could also buy some commercially available slug-repellant copper mesh that has been designed specifically for this purpose.
Remove Debris from Ground
If you find that you have recurring issues with slugs year to year, incorporate a bit more lawn maintenance into your seasonal routine to create a less inviting environment for the slugs.
After the soil thaws in spring, you should remove organic debris from the ground such as fallen leaves or old mulch; slugs like to live among matter like this, as well as lay their eggs in it. You should also give your garden a thorough raking at this time of year, as it helps to clear away the debris and soil-borne eggs.
Only Water When Necessary
Following a proper watering schedule, you should only water your lawn when absolutely necessary. Slugs are drawn to overly damp places, so minimal watering will help to create an uninviting environment for them.
A further tip is to always water in the morning, as the water will gradually evaporate during daylight hours; slugs are attracted to plants and gardens that are consistently moist overnight, so watering in the morning helps to reduce the likelihood of these conditions.
Reduce Number of Plants that Slugs Love
If possible, try to avoid growing plants in your garden that slugs are highly attracted to. This includes basil, beans, cabbage, dahlia, delphinium, hosta, lettuce, marigolds, and strawberries, to name a few.
Instead, grow more plants that are known to be slug repellant – you can refer back to the previous sections in this article to learn the types of plants that slugs tend to favor and those that they tend to avoid.
Encourage Populations of Natural Slug Predators
There are a lot of animals that behave as natural predators for slugs. Chickens and ducks enjoy feasting on slugs and their eggs. Birds, particularly songbirds, also love to eat slugs, so consider installing a birdbath or some birdhouses around your yard if you have the space in order to encourage them to spend time and feed in your lawn or garden.
Other animals that like to feed on slugs include frogs, toads, turtles, newts, salamanders, snakes, hedgehogs, shrews, ground beetles, rove beetles, praying mantises, and fireflies.
How to Get Rid of Slugs
Tip: Slugs prefer to spend time in damp, dark places, such as underneath boards, flowerpots, garden debris, flowerpots, or other similar areas that you have in your yard. Make sure to target these areas primarily when applying any of the natural or chemical solutions to get rid of slugs where they are most likely to congregate in the highest numbers.
Remove Slugs By Hand
The most direct way to get rid of slugs is to manually remove them by hand. First, determine where the slugs are gathering en masse by venturing out into your yard after dusk. Wearing rubber gloves, pick up each slug you find by hand; either place them into a container to later release them elsewhere or kill them by dropping them into a container filled with salty water.
To ease the removal process, you could place a wet piece of wood or wooden plank near likely slug hotspots and then wait until the early morning; the slugs will finish feeding and gather under the piece of the wood, which you can then pick up to reveal them underneath.
If you’re too squeamish to do this by hand, try using chopsticks or a large pair of tweezers.
Salt Slugs By Hand
Another method of removal carried out by hand is to hunt out the slugs and sprinkle them with salt, as this will kill them on contact instantly.
The salt will kill the slugs by drawing the water out of their bodies. This happens via an organic process known as osmosis, which in turn causes them to dry out and die.
This method is highly effective at killing slugs quickly but is not a humane way of getting rid of slugs. It’s an extremely cruel way to kill slugs.
An abundance of salt can also cause damage to growing plants and may render soil unusable for growing years after application.
Kill Slugs With Alcohol
Alcohol will kill slugs on contact. It acts as a surfactant or ‘wetting agent’, meaning that it penetrates the slugs’ outer waxy coating and then kills the slugs once their bodies make contact with the alcohol.
Make a DIY alcohol-based insecticide by mixing 70% alcohol in equal parts with water, or 95% alcohol in a ratio of 1 part alcohol to 1 ½ parts water.
The best type of alcohol to use for this method is ethanol (grain alcohol); although isopropanol (rubbing alcohol) can also be used, it is slightly less effective and you also need to make sure to choose a product that is free of any other additives.
Plant Sacrificial Trap Crops
You can control the number of slugs in your lawn or garden by dedicating one area of the yard to growing crops that slugs are highly attracted to. This process is also known as companion planting.
It may seem counterintuitive, but by planting these more attractive crops, you can create a sort of trap that will attract all of the slugs into one place. This saves your other crops or plants from being eaten, and makes any further manual methods of removal much easier. The best crops to be used in this method include chervil, marigold, or thyme.
Set Up Beer Traps
Setting up beer traps is a common method used to get rid of slugs that you can DIY easily and for a low expense if you have a small to medium-sized yard. They are attracted to the smell of the yeast, causing them to fall into the trap and drown.
Take a clean, shallow container (e.g. a cleaned tuna can, yogurt pot, or tub of butter) then bury the container near the slug hotspots in your yard. When you bury the container, ensure that it is sticking out of the soil about an inch high.
If you want to place multiple traps, make sure to place the containers about 3 feet apart from each other. Fill the container with a beer of your choice; any beer will work, but darker beers with a more yeasty aroma will be more effective for this purpose.
Leave the traps overnight then dispose of the contents of the containers into your trash or compost the following morning.
The drawback with this method is that it often attracts and kills lawn- and garden-friendly insects in addition to the slugs, so it’s only recommended to be used in the case that you have a severe infestation.
Also, as the traps need to be placed about every 3 feet throughout your garden, this method can end up being relatively costly and labor-intensive if you’re working with a larger space.
Set Up Fruit Traps
You can make effective traps out of citrus fruits to get rid of slugs and keep them away from your plants. The slugs are attracted to the sweet scent of the fruit and gather in the trap, enabling easy removal the following day. The added benefit of this trap is that it is much less harmful to other types of garden-friendly insects as opposed to a beer trap.
To create a fruit trap, take half of a citrus fruit and scoop out the inner flesh, leaving a hollowed-out peel. The best fruit to use for this is grapefruit, but a hollowed-out cantaloupe or orange rind will also work well. Place the hollowed peel of the fruit upside down near the slug hotspots and leave overnight.
The next morning, remove the fruit half and dispose of it. Either place it somewhere far away from the garden or throw it onto your compost pile.
Organic Slug Pesticide
There are a few organic compounds that can be used to kill slugs, eliminating the need for the application of a chemical pesticide.
Slug pellets containing ferrous phosphate or iron III as their active ingredient are an organic method to kill slugs. These pellets interfere with the calcium metabolism in the gut of the slugs, causing them to stop feeding, killing them off after 3 to 6 days.
The pellets are harmless to other types of wildlife, and any uneaten pellets will break down over time into a form of iron and phosphate that can be taken up by surrounding plant life. With that said, the pellets should still be used sparingly.
Chemical Slug Pesticide
Note: Chemical slug control products should only ever be used as a last resort as they are highly toxic and can cause damage to the nearby environment, as well as cause harm to pets, friendly insects, and other types of wildlife.
The main type of chemical control product used to combat slugs is a pelleted pesticide containing an ingredient called metaldehyde. This pesticide attracts slugs and then kills them by destroying their protective layer of mucus, which in turn debilitates their mobility and digestion.