Colourful yellow snail on window glass

Slugs and snails: should we love these gliding gastropods?

Our award-winning guest blogger Esther Woolfson speaks up on behalf of snails and slugs. She delves into their important role in our gardens.
  Published:  20 Nov 2017    |      3 minute read
Golden-coloured snail reflected on wet surface
Snails are more abundant after the rain

Autumn. Misty, lightless. Everything is damp, fading into smoky grey beneath a strange white sky.  A thin net of moisture lies on leaves and grass as I stack logs for winter. While I work, I have to move  snails - abundant after recent rain - carefully from the stones under my feet, because I don’t want to squash them.

Adult snail and baby snail on twig
Adult snail and baby snail on twig

Shelter and hibernation

I know they like to return to familiar places. But when it comes to the desires of snails, it’s pretty much guess-work.

Holding them by their shells, I see their quick withdrawal from movement and light. Snails are incredible creatures, like most inhabitants of the natural world, complex and fascinating, capable and indomitable as they glide about their purposes.

I decide they’ll probably like dark corners, walls, the sides of the moss-covered birdbath - places that seem secluded and safe. I plant them as securely as I can and go back to wood stacking.

Snail on green moss
Snails are particularly temperature and moisture sensitive

Snails are particularly temperature and moisture sensitive. In summer, if it’s too hot and dry, their heart and metabolic rates slow drastically. They seek out places where, securely glued on, they can wait for the heat to pass. 

Now, as winter approaches, they’re preparing to hibernate. The same slowing takes place, the same search for safe places to see out the cold. 

In preparation for heat or cold, snails seal themselves protectively into their shells, constructing a barrier, or epiphragm, across the entrance. This layer of mucous prevents them from losing moisture and maintains their temperature.

Snail shell closed, showing epiphragm barrier
Snail shell closed, showing epiphragm barrier

In summer, the layer of epiphragm is like a thin membrane of single-glazing across their door. But in winter, it’s double or triple glazed, the epiphragm drawn neat and tight and weather-proof - such perfect design.

I move a few slugs, too, to places of safety. Distracted by the onslaught of hatred directed against garden molluscs, it’s easy to forget that they’re part of a large, important and diverse class, the Gastropoda. And they have a vital role in the natural balance of our natural ecosystems.

Snail on red watering can
Snail on red watering can

Consumers and consumed - the role of snails and slugs

Snails and slugs eat their steady way through rotting vegetation, and they act as a valuable food source for some of our most beloved birds, as well as frogs, toads and hedgehogs.

Is it fair that they attract peculiar vengeance for their entirely natural behaviour of eating plants which we sow in exactly those places they like to frequent?

Some gardeners encourage birds or hedgehogs to keep snails at bay. My own method of controlling slugs is to do nothing at all. Don’t ask me why but it works. My slugs seem moderate in numbers. So a hosta gets nibbled. Worse things happen.

Dark brown slug eating a cut yellow flower
Slug nibbling on a cut flower

If they change their habits, I’ll plant red clover to attract them, or put copper edging or ash or some other physical deterrent around the plants I want to protect.

I won’t use slug pellets which poison the species that eat them. Nor will I stick pins in them or chop them in half, drown or burn them, or worse as suggested by many gardeners. Studies have shown that molluscs feel more than we might imagine.  

Some gardeners, including TV presenter Alys Fowler, have even learned to love slugs for helping her weed out weaker plants.

Spotted leopard slug on piece of decayed wood
Leopard slug - mostly eats dead plants or fungi

The slugs prepare for winter too - some will hibernate deep underground, and some, having laid up to 450 eggs, die in autumn.

As my precarious stack grows and tumbles again, it occurs to me how much more efficient snails and slugs are when it comes to this business of winter preparation. And I feel a kind of common purpose. All of us, mollusc or not, are readying ourselves for winter, slowing in rhythm with the movement of the Earth.

Esther Woolfson is the author of Corvus - A Life With Birds and Field Notes From a Hidden City - An Urban Nature Diary. She lives in Aberdeen with an elderly rook, a young crow and the 14 inhabitants of a dove-house in the garden.

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