Do Slugs freak you out? Do they make your skin crawl? You are not alone. Slugs, or “snails without shells,” have been the subject of many urban legends and horror stories throughout history. They can be found all over the world, but there is still much to learn about these fascinating but ugly little creatures! Below we answer the question “Are slugs Poisonous?” and other frequently asked questions about slugs that may help ease some of your concerns.

Slug on Cabbage Leaf
Affiliate Disclosure

1. What Are Slugs?

Slugs are non-parasitic, invertebrate molluscs of the Order Aglajida. Slugs belong to the phylum Mollusca and are closely related to clams, oysters, snails, and squid. They have smooth, slimy skin which can be encased in either leathery or calcareous shells depending on species and our planet’s seasons (usually slugs produce their own mucus protectors).

2. How Many Types of Slugs Exist?

There are over 40,000 gastropod species with the majority being marine gastropods – meaning they live in water. Most different kinds live near water but some live in deserts, underground, or even underwater. Marine gastropods include sea slugs, nudibranchs, and bubble snails as well as many other lesser-known species.

3. Why Are Slugs Slimy?

Many people find that slugs do feel wet when touched because their skin secretes a mucous substance. Slug slime contains proteins that are important for salt balance in the slug’s watery body. These proteins also act as a lubricant, allowing slugs to slide over surfaces more easily, and are thought to have evolved from the protein slime that covers many sea creatures like jellyfish. The mucous protects them against dehydration by trapping small amounts of moisture on their skin surface so they can drink it through their thin “tongue.”

Did you know? Slugs do not need to drink water because most of their moisture comes from dissolved minerals in their food sources.

4. What Do Slugs Eat?

Slugs are omnivores. They feed primarily on plants although they will also sometimes consume animal matter, like small insects or dead animals. The mollusc’s mouth is located at the centre of its underside and it has a radula that rasps against plant tissues to create a feeding grove before it secretes digestive enzymes from glands in its head that break down cellulose into usable sugars for itself.

Different types of slugs have different diets, but they all consume vegetation such as vegetables, fruit, or other green plants by scraping them off the ground or from surfaces like animal droppings.

5. Which Countries Can You Find Slugs In?

Slugs have a global distribution, meaning they can be found on every continent except Antarctica. In North America alone there are more than one hundred different types of slugs-most notably the blackish-brown banana slug which lives in moist forests from Alaska down to Florida.

6. How Big Do Slugs Grow?

Slugs vary in size based on species, but the smallest slug is considered to be Armadillo Palliser Sackless Slug from Southeast Asia. The average length for an Armadillo Palliser sackless slug ranges from 6mm to 23 mm, with a distinctive pointed back. The largest known Slug “Limax Cinereoniger” can grow to up to around 18-20cm long, with the heaviest documented specimen weighing in at just over 450grams.

7. How Do Slugs Reproduce?

Slugs are hermaphroditic, meaning they have both male and female sexual organs. They produce spermatophores for mating because the act of giving sperm to another slug is more costly than receiving it from an individual who has already done so. The two slugs will then come together and exchange spermatophore packets with each other before fertilization occurs internally in one or both partners during their embrace.

The meeting between the slugs can last up to 40 minutes while they explore each other’s bodies using chemoreceptors on their tentacles as well as tasting through contact by closing their sensitive lips around one another to confirm mutual interest in reproduction.

8. Why Do Slugs Exist?

This is an existentialist question that I am not sure anyone can truly answer but I will give it a go. Slugs are part of nature and they exist because life needs to be in balance for the food web to exist. As you may know, many plants depend on slugs for pollination and seed dispersal. If there were no slugs, then there would be no plants which eventually leads to no animals as well since all animals ultimately rely on higher-level survival loops that begin with plants.

Simply put, if we removed every last slug from the planet this could well become a post-apocalyptic nightmare scenario where the balance of nature is completely out of whack and everything will eventually die.

9. Are Slugs Poisonous?

Slugs are not poisonous to humans; however, they can be toxic to pets and wild animals. Slugs have no toxin or poison glands and the slime that they produce is made from mucus and serotonin which will make them taste bad to predators such as cats if they are eaten. Since they are molluscs rather than insects, their exoskeletons do not have any stings either.

Another thing to consider is that although they may not be poisonous, they also carry a lot of diseases such as salmonella and E. coli, which can be transmitted to humans through contact with the skin or by eating them raw.

10. Why do Slugs Come Out at Night?

Slugs are nocturnal. Recent research has shown that along with avoiding predators that are more active during the day, it is also a way of avoiding the heat, so they do not become dehydrated. Slugs often prefer dark, cool places in which to live, like the ground under your porch steps. They also prefer moist environments where they can find suitable food for living off. This means that slugs come out mostly at night when it is cooler due to moisture from watering plants and the dew on plant leaves will provide a moist surface for them.

Additionally, less sunlight outdoors during the nighttime hours is preferable for slug survival because it limits their vulnerability to predators and offers an easier time moving around without being noticed as easily.

11. Why do Slugs Die From Salt?

Slugs have a lot of water inside them, and the cells that make up their skin are highly permeable. When salt comes into contact with a slug and the mucus they secrete, this creates a saltwater solution. Osmosis occurs when this happens because there is more concentrated salt outside than inside. The slug’s body will try and compensate to even things out by passing water from within to dilute the solution.

If a Slug must try and dilute too much of this saline solution by using its internal fluids it would lose too much liquid due to osmosis and then shrivel and die due to dehydration.

12. Do Slugs Hibernate?

No, Slugs do not hibernate although they do take part in a form of dormancy during their winter period. A true hibernation is a form of torpor, which we see in many other animals but slugs do not enter this state. Slugs living in temperate regions go into lean physiological states as the weather begins to cool. At this point, they stop eating and start going through drastic fat loss by shedding most of their body surface cells – right on down to the gut lining.

These changes are much more pronounced than you would see with animals like hedgehogs, who only reduce food intake and then shift into a shallow sleep.  

13. Do Slugs Bite?

Technically, Slugs do not bite. They have a radula, which is a ribbon-like organ used to scrape away loose algal films from rocks and other surfaces. It is also used to create suction as they drag themselves along the ground. If you place your hand in front of their mouth (where the radula is) for more than about thirty seconds, then slugs will eventually leave microscopic damage on your skin called dermatosis.

14. Why do Slugs Like Beer?

For slugs, beer encompasses the characteristics that are usually found in rotting fruit and flowers, which are a slug’s favourite foods. Beer is high in sugar and contains yeast from the fermentation process and slugs love it.

15. Are Leopard Slugs Bad?

No, although many Slugs are garden pests, not all Slugs are bad, in fact, the leopard Slug can actually be a beneficial presence in your garden. Leopard Slugs will leave your plants alone and they will eat other more destructive Slugs whilst also eating rotting plant/ animal matter and prey on other pests such as Aphids. Lastly, Leopard slugs do not bite or sting humans, so it is safe to have them in your garden!

16. Do Slugs Lay Eggs?

Yes, Slugs do lay eggs. A slug can lay up to 500 eggs in a single season, but these are usually laid in clusters of 20 or 30 at a time. Slug eggs are considered to be particularly resilient to adverse weather conditions. Slug eggs can stay dormant for many years until they are triggered by a favourable climate and the presence of prey, which in turn triggers them to hatch into slug larvae.

17. Do Slugs Poop?

Slugs do indeed poop. A Slug’s digestive system is a complicated machine much like our own that converts food into waste. Food goes in, gets mixed with digestive juices, and is digested before being excreted back out. After a slug has eaten and digested food, it will excrete from its anus. The colour, along with the way the scat leaves vary depending on what was consumed; sometimes coming out as mucus strings or more solid dense patches of material.

18. Do Slugs Feel Pain?

The question of whether or not slugs feel pain is a difficult one to answer, due to the lack of scientific real evidence on the subject. One known study that has been done on Slug sensitivity reviewed a series of behavioural and physiological responses in species within this group. These reactions were studied under three conditions: A) control (sensory stimulation absent), B) low-level stimulation (low-intensity prodding sensed by limaxes), C) high-level stimulation (extremely high-intensity prodding that was painful to at least some arionid species). The conclusion of the study was that all three slug species responded differently when exposed to various levels of sensory stimuli, with more vigorous reactions occurring when the stimulus was greater than baseline.

19. Do Slugs Eat Tomato Plants?

Yes. The slugs will eat the leaves, flowers, and even the fruits themselves if they have access to them. If you find a slug in your tomato garden it is best to remove it as soon as possible because slugs can devastate plant life. If your garden is lacking in its usual predators, they can chew their way through your greenery very quickly.

20. Do Slugs Eat Cucumber Plants?

Like your tomatoes, Slugs will certainly eat your cucumbers if they are in the garden. If you find a slug, remove it as quickly as possible or risk losing your crop to their appetites. However, there is one thing about these cucumbers which makes them difficult for snails and slugs to devour: namely their skin! The waxy exterior protects these plants much more against hungry pests than other species. This means less work for us humans when we go out into our gardens at night with flashlights looking for invaders.

21. Do Slugs Eat Busy Lizzies?

Slugs will eat the leaves of Busy Lizzies, especially if there are no other foods nearby for them. Slugs preferentially feed on moist greener plants and vegetables because these have higher water content and thus can be more easily filtered through their digestive system. If you see Slugs around your busy Lizzies, relocate them immediately!

22. How Long do Slugs Live?

Slugs can live anywhere from 1-5 years, depending on the species and environmental factors. Some slugs, such as the grey garden slug, can live up to 5 years. Other species, such as the banana slug, have a lifespan of only 1 year.


Slugs are a vital part of our ecosystem that we cannot forget about if we want to maintain any semblance of balance in nature, so it is important not to kill slugs for no good reason! However, they are also capable carriers of disease so caution should always be exercised when interacting with them. So next time you see one crawling across your garden do not go out there and squash it – instead just try and relocate it elsewhere! Alternatively, get some Leopard Slugs to predate any nuisance Slugs to keep that natural balance.

Facts about Slugs Infographic

Garden Doctor Tips

“Surprisingly, Leopard Slugs are good for the garden, they will predate some of the more annoying pests you may find!”

“It is best not to kill the slugs and just move them on elsewhere unless you introduce some predators to let nature take its course!”

“To keep slugs away from your veggies, leave some rotting plant matter somewhere in your garden and hopefully they will be more attracted to that!”

“Although slugs are not poisonous, we recommend handling them with gloves on as they have been known to harbour harmful diseases!”


Trevor Wright is not just a seasoned horticulturist; he’s the esteemed Garden Doctor. With a BSc in Horticulture and years of hands-on experience in the soil, Trevor has become a trusted mentor for all things gardening. As the founder of Garden Doctor, he’s committed to clarifying the intricacies of gardening, offering straightforward advice that’s rooted in years of practice. His writing is a garden of how-tos, savvy insights, and comprehensive guides that enable individuals to nurture and grow their garden dreams. When he’s not knee-deep in garden beds, Trevor is at his keyboard passing on his green-thumbed wisdom to budding gardeners, ensuring that the legacy of sustainable and joyful gardening blossoms far and wide.

More You Might Like