Are Slugs and Snails Insects?

Slugs and snails are two garden pests that can be found throughout the world, with around 1200 different species in North America alone. These slimy, slow-moving creatures are well known for their ability to consume large amounts of vegetation, but many people are still confused about what they actually are.

Are slugs and snails insects? And if not, then what are they?

What are slugs and snails?

Slugs and snails are not insects. In fact, they’re a different type of animal altogether. Insects belong to the phylum Arthropoda, whereas slugs and snails are found in the phylum Mollusca, meaning they’re more closely related to squids than most other bugs found on land.

This group is one of the most diverse in the animal kingdom and includes a wide range of soft-bodied creatures including octopi, oysters, and clams. Slugs and snails belong to the class Gastropoda, which is the largest group within the phylum Mollusca.

Within the Gastropoda class, there are two members; snails (which carry a shell around with them) and slugs (which don’t).

All about slugs and snails


The main distinction between slugs and snails is in their appearance. Although both have soft, elongated bodies and are usually gray or brown in color, only snails carry a shell on their backs for protection.


Both slugs and snails move by gliding (slowly) along on a slimy ‘foot’, a long sheath of muscle on the underside of their bodies. This muscular ‘foot’ constantly oozes a slippery mucus to aid movement, which is why slugs and snails always leave a silvery trail in their wake.


The slugs and snails you’ll find in your garden all favor damp, cool environments. They are most often found on rotting logs, inside piles of leaves and compost and in moist earth (like flowerbeds).


The gastropod diet is the very thing that makes them so unpopular among gardeners. These common pests feast on all kinds of foliage and can cause significant damage to fruits, vegetables, and ornamental plants. Their food of choice is often leafy crops like lettuce and cabbage, and the young, tender leaves of new plants.


Slugs and snails are hermaphrodites, meaning they are born with both sets of sex organs and are all able to lay eggs after mating.

As with everything else, garden snails their time mating; in fact, the process can take up to 12 hours! Three to six days after fertilization has taken place, the snail deposits up to 120 white, spherical eggs. Snails reproduce most frequently during the summertime when the warm, humid weather creates the perfect conditions for egg production.

In optimal conditions, snails may lay eggs every month, which will hatch into baby snails after around two weeks.

The gray garden slug has a similar lifecycle, though their eggs are clear and jelly-like.


These eggs are highly resilient and can survive even in cold, dry conditions, so they are able to overwinter(unlike adult slugs).

Once hatched, gray garden slugs live between nine and thirteen months and lay up to 500 eggs over the course of this lifespan.

What eats slugs and snails?

Slugs and snails are an important part of the ecosystem, as they are a valuable food source for many bird, amphibian, insect, mammal and reptile species.

Song thrushes, hedgehogs, newts, and toads all dine on slugs and snails, so encourage the presence of these species in your garden if you’re having trouble with gastropod control!

How are slugs and snails different from one another?


Slugs and snails are very similar in terms of their appearance, diet, mating habits and habitat. The key difference between the two is the presence or absence of a shell.

Land snails carry a shell on their back, which they retreat into for protection. This feature is absent in slugs, although some species have a very small, or sometimes internal shell.

How can you keep slugs and snails out of your garden?

As with most other pest species, the key to effective slug and snail control is a good preventative strategy. A well-implemented integrated pest control plan in the most effective way to keep slugs and snails out of your garden so your plants can thrive this summer.

Keep moisture to a minimum

Gastropods love moist environments, which is why so many of them end up in your flowerbeds. It’s important to keep your plants watered, but over-watering can do more harm than good and creates the perfect habitat for slugs and snails. Water your plants only as much as needed to keep slugs and snails away from your crop.

Anti-slug and snail pellets

Slug and snail pellets, powders and sprays are an effective way to kill these pests and keep them off your plants. However, many of these products use metaldehyde, a compound that is toxic to dogs, cats, and other wildlife.

If you want to reduce the number of slugs and snails in your garden without decimating every other creature in the vicinity, look for pellets containing iron phosphate. This compound is made up of naturally-occurring ingredients (iron and phosphate) and is less likely to harm non-target species.

Set up a slug barrier

A slug barrier can be a great way to keep gastropods off your vegetables; not only is it effective, but it’s also non-toxic and easy to set up.

Simply place copper strips around plants to keep snails and slugs away. Attempting to cross the copper wire will give them a mild electric shock, so they’ll stay on their side of the strip and leave your plants be.


Are slugs and snails insects? We’ve all encountered them at some point, but how many of us stop to consider the exact nature of these creatures?

The truth is slugs and snails aren’t insects; they’re actually Gastropods belonging to the phylum Mollusca, which also includes squid, mussels, and clams. There is little difference between slugs and snails, with the notable exception of the shell – but both can be bad news for your garden!


Molly Skooter

They might be in a different phylum, but I think in our society they fill the same role as bugs: you can put them in a jar with a leaf, they show up around your plants, they are small.

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