Slugging it out on the Plot

We lift the lid on the compost bin to shed light on a diverse army of creatures munching away at yesterday’s input. In among the crowd are slugs and snails who compete with the woodlice, millipedes, worms and others to see who can munch the most.

We all know that a slug is essentially a snail without a house on its back and a mortgage to pay, but what else do we know about these creatures? Many of us focus on their removal and a ‘slug free plot’ but is that possible and what is the size of the slug and snail army we face?

What we must recognise is that slugs are clearly the ‘unseen’ enemy. Some 95% of the population are in fact underground, nibbling away on seeds, roots and laying eggs and unfortunately not taking on the bindweed! An average garden contains around a staggering 20,000 slugs, and cubic metre can contain around 200 alone, or an acre some 392,040 slugs. One individual field slug has the potential to produce about 90,000 grandchildren. These gastropods form the second largest class in the animal kingdom and there are some 30 different varieties in the UK. So they are a formidable army!

Slugs can live live up to 5 years and can lay 20 to 100 eggs a time and 400 to 500 a year. It is easy to see why therefore they continue to attack in waves and a few casualties hardly affects their potential to consume everything before them.  

We know who won the fabled race between the hare and the tortoise but how would the slug fare? We see those slimy trails but how long do they take to cross the average plot? They usually move at a steady pace but can cover 50 yards per hour or 1.3cm per second. So Usain Bolt covers 100 metres in under 10 seconds whilst the slug would take 2 hours, making it one of the slowest creatures on the planet.

We all know their diet which may leave the odd vegetable but is not too discerning and an individual slug can consume around forty times their weight in the space of a day. Now that’s what I call greedy and you never see a catwalk stick model among them.

When not destroying healthy plants, most slugs eat decomposing vegetation, but trying to train them to stick to this diet and leave plants alone is impossible. Some argue that their love of decomposing material makes them a vital part of the ecosystem, others that if they can’t be trained, they remain gardener’s enemy number 1.

They love the dark and dampness so after heavy rainfall and at night you are likely to find more slugs in your garden. So why do some advocate watering the plot last thing at night? They drink water and that in turn gives them that slimy coat and avoids them drying out. They can also stretch to approximately twenty times their length in order to squeeze through gaps.

British gardeners use over 400 billion slug pellets every year and although many alternative solutions exist, an army of slugs still keep coming over the trenches at night. My father in law used to keep a spoon in the garden for hurling slugs catapult style out of the garden but he didn’t realise that you have to hurl them at least 20 metres to ensure that they lose its bearings and are less likely to return. Snails’ homing instincts only cover short distances. However, we forget that slugs are like cave explorers and instead of a rope, they can return via that unique slimy scent trail. I wonder how the ones my father in law ejected found their way home without their trail?

Deterrents include vinegar which removes slug slime and can help if included in slug sprays, copper tape which generates a shock to their system, wood chip, gravel or crushed eggshells, which presents a rough surface they dislike. We all know what salt can do to slugs, so what about a sea salt spray across open ground? Coffee grounds also are said to produce both a hostile surface and pungent smell to the slugs, but I think mine quite like hanging out in the new café culture I have created.

Not only the French like their snails. Non-French predators such as hedgehogs, rodents, some bird species, slow worms, foxes, badgers, violet ground beetles and Devil’s coach horses and other ground beetles also do. But do we really want to encourage rodents onto the plot? I must make a note to speak to Freddie Fox to ask him to increase his pack’s night patrols on my plot. Mind you, I would have to deal with the increased poo deposits.

It’s strange that foxes can eat them but that slugs can cause severe problems for dogs as some slugs carry lungworm, a parasite which affects dogs’ heart-rates and breathing and can even be fatal.

Slugs are also a Dentist’s nightmare in having some 27,000 teeth but when their teeth wear out new rows move forward and replace them, conveyor-belt style. Now why can’t we do that? Their cousin, the sea-based cone snail, is one of the most deadly creatures in the world with a single sting even able to cause death.

So what else may we not know about Slugs?

Well, they avoid strong smelling plants with hairy stems and lavender, rosemary, cranebills or herbaceous plants aren’t on their a la carte menu. But nearly all the vegetables we grow are!

They are almost completely blind and can’t hear anything so navigate life through their sense of smell which they do through their body and they can detect from a few metres away.

They hibernate during winter and are only active when the temperature is above 5°C. After all what’s the point of going out on a forage when it’s cold and there is little to eat.

Finally, there is their slime trail which absorbs water and can be exceedingly difficult to wash off your hands. What is fascinating, well to me anyway, is that this slime contains fibres. I have often wondered how slugs can climb what must appear as daunting as climbing the North face of the Eiger and cannot fall off. It’s down to the fibres. This also enables them to glide over glass shards or even the edge of a razor blade.

The one thing I have learnt is that the invasion of the Slugs is a battle that almost certainly can’t be won, only contained.