An overabundance of pests is a sign that the natural equilibrium is disturbed. Normally predators and prey populations keep each other in a natural balance.
Pests can only multiply explosively when they and their juveniles are safe and rarely threatened by natural predators.
Therefore slug or snail population booms can only occur if they do not encounter enough natural enemies.
As a result it is necessary to attract their natural enemies and to provide suitable habitats in the garden.
- 1 Prevent the slug booms through biodiversity
- 2 Which animals eat slugs and snails?
- 3 How to increase the biodiversity in the garden?
- 3.1 More native plants
- 3.2 Wild corners
- 3.3 Garden ponds
- 3.4 Cairns
- 3.5 Dry stone structures
- 3.6 Brushwood piles
- 3.7 Hedges
- 3.8 LEDs or better no light at all
- 3.9 Less tidying up of beds in autumn
- 3.10 Deadwood
- 3.11 Less and less digging
- 3.12 Open sandy areas
- 3.13 Mow wisely
- 3.14 Abstain from chemical crop protection
- 4 Conclusion
- 5 Further methods to control slugs and snails
Prevent the slug booms through biodiversity
It is sometimes said that slugs taste bitter (especially the Spanish slugs) and therefore many animals won’t eat them.
This is not true. Slugs have many natural predators. But for various reasons, these enemies have disappeared from the gardens.
More information here: Causes of slug / snail booms (soon).
However, there are quite a few measures to lure the snail eaters back into the backyard.
Which animals eat slugs and snails?
Particularly industrious snail hunters are for example various species of insects, which today are threatened with extinction and which are already extinct in many areas.
Also hedgehogs, toads, moles, lizards and songbirds are natural enemies of slugs and snails.
But these animals are suffering from the decline in the insect population, which has become increasingly devastating since the introduction of chemical pesticides.
Many insects are not only sensitive to insecticides but also to herbicides and fungicides.
They suffer a great deal since more and more poisons are introduced into agriculture and horticulture.
This development is alarming and there is a need to take decisive counteractions wherever possible.
Because every garden can become a small ark for endangered animals and plants.
Species protection in the garden not only helps the animals, but also the gardener.
A high diversity of species prevents the undisturbed spread of pests.
Thus if a garden is rich in biodiversity a slug or snail problem would be nipped in the bud.
Natural enemies of slugs and snails:
- ground beetles
- leopard slugs
- roman snails
- and more
The more species live in a garden, the lower the risk of a pest infestation.
More information about insects that eat snails and how to promote them here: insect-friendly garden (soon)
How to increase the biodiversity in the garden?
There are many ways and means to increase biodiversity.
These are some:
- Offer as many indigenous plants and trees as possible.
- Create wild corners in the garden, which are left to themselves.
- Create garden ponds with rich bank planting.
- Layer piles of stones with many cavities.
- Build dry stone structure in sunny spots (drystack).
- Pile up leaves in undisturbed silent secluded locations.
- Create blooming hedges with native plants or dead hedges.
- Minimize garden lighting and where necessary use only warm white LEDs.
- Do not clean the beds in autumn and leave plant stems until spring.
- Leave deadwood and lay out different varieties coarse woody debris.
- If possible, do not dig up the soil, only open the surface a little and loosen the subsoil.
- Offer small open sandy areas with open water close by.
- Mow the lawn rarely and environmentally friendly (bee-friendly).
- Withstand from chemical crop protection.
These are the main things everyone could do to promote biodiversity and to create an ark in the backyard.
More native plants
The basis of life in the garden are the plants, because they stand at the beginning of many food chains.
A lot of insects rely on very specific plants to be able to survive.
Therefore, it is important to have as many different native plants in the garden as possible.
With their flowers and plant saps, herbs, trees and shrubs nourish all the insects, which become a food source for almost all larger animals.
That is why it is so important to let the plants bloom and to offer the widest possible range of flowering plants throughout the whole year.
A tidy garden is a disadvantage for many animals, as they find little food in it and also lack places to live and hide.
Therefore, it is a great help to leave some places in the garden to themselves and to allow a certain amount of disarray.
These places do not have to be big. Even a small pile of branches or a cairn makes many animals happy.
It is important to leave these spots as undisturbed as possible, then their residents will feel most comfortable.
Almost all animals rely on an accessible water source to survive.
Therefore, garden ponds are always a great help to increase the biodiversity even further.
Not only does a pond provide a space for special animals, also many plants need this habitat.
The bank of a pond can be planted with a great variety of native water-loving plants.
It is advisable to refrain from fish, as they would eat up the snail-eating amphibians and their spawning.
Only in a very big pond it would be possible that fish and a variety of amphibians could live together.
Of course it would be best to create different ponds, then fish, toads and newts will have their space to flourish.
A small pile of rocks which includes tiny cavities is the perfect home for many animals.
If you wish to create a professional cairn, then you pick a sunny spot and dig a 20 inches (30cm) deep hollow which you fill with sand and gravel.
On top you layer large and small stones onto each other and thereby create many cavities and hiding spots.
After you cover the shady side with sand.
Then many animals will make themselves a home there and might even be able to endure the winter.
Dry stone structures
A dry stone structure or wall, which can heat up in the sun and has many cracks and cavities, provides a home for countless small and large living beings.
The construction of the wall, however, requires a little experience. Otherwise it could quickly collapse and harm someone.
Mostly you need a solid foundation and a good skill in layering. It is advisable to inform yourself well in advance.
A pile of twigs and branches are easily stacked up and can be a paradise for wildlife.
Therefore, the custom of shredding the branches in autumn or spring and removing them from the garden is a bad habit in regard to species protection.
The garden looks tidy if you dispose dead plant parts in this way.
But it is advisable to leave at least a part of it (preferably all of it) in the garden and thus to offer many animals a niche to live and shelter during wintertime.
If the pile is covered with foliage not only the hedgehog will feel at home, but many insects will also find their way inside.
Hedges of flowering native plants and shrubs are a source of life and therefore a gift for any garden.
Due to the fact that a hedge is most of the year left alone. Many species can live in it undisturbed and multiply peacefully.
If the hedge flowers it also feeds many animals and increases the attractiveness of the entire garden quite a bit.
A special treat for wildlife: deadwood hedges
Birds and many other animals also love deadwood hedges, as they can find special food and safe shelter there.
For this purpose, branches and twigs are piled up to form a kind of hedgerow which is held in shape with wooden posts.
LEDs or better no light at all
Most nocturnal insects are very sensitive to artificial light sources.
Particularly short-wave blue light attracts them magically and normal lamps are thus often fatalities for all kinds of moths and flies.
Therefore, it is extremely helpful to use only warm white LED bulbs (1000 – 3000 Kelvin), as they emit no UV light and only a few blue parts of the light spectrum.
Basically, it would be best if you could abstain from nocturnal lighting of the garden.
Motion detectors and other light sources that you do not want to miss could be positioned and adjusted in a way that they can not trap the animals.
Instead of trapping them, you could help them and offer different insect hotels.
Less tidying up of beds in autumn
It can not be said often enough that a large number of insects rely on dead plant remains to overwinter in or below them.
Therefore, it is particularly important not to clear everything from the beds in fall.
To help the animals as much dead plant material as possible should be left behind.
You’d be doing nature a favor to relax and leave them until spring.
For example, plant stems or dead flowers are a vital necessity for many animals (eg. wild solitary bees).
The beds should be cleaned in spring, when the winter is over and life starts to flourish again.
This practice may disturb some aesthetic sensibilities, but it is a simple measure and the natural world will benefit enormously.
A dead tree trunk is an indispensable source of life for many animals.
Therefore, it is particularly useful to offer coarse woody debris of a variety of different tree species in hidden spots of the garden.
This is easy and for a little effort, it creates a small habitat and that is vital to many insects (eg. beetles and solitary bees).
And the bigger the pieces of wood and the more tree species you could offer, the better.
Less and less digging
The soil itself is also a habitat for many animals.
Insects pupate in the interior of the earth and sometimes live there for several years before they enter the Earth’s surface as all sorts of different beetles.
Therefore, it is important not to disturb this habitat unnecessarily.
The digging over of the soil harms many ground dwellers as it breaks up their homes.
This is why you could try to do without it or to minimize it.
Most of the years it is enough to break up only a tiny top layer. With appropriate tools, the deeper layers of the subsoil can be loosened with special long spades.
Open sandy areas
There are some animals that need an open sandy surface.
For example, solitary wasps or solitary bees need these sites to get construction material for their nests.
Some species will also use this place to dig up holes and caves to breed their offspring (eg. digger wasps or beetles).
It is good if also an open water source in the vicinity.
Then the animals can make themselves a kind of mortar, with which they can built their nests and, for example, close plant stems or their room in an insect hotel.
One of the favorite hobbies of many gardeners – that’s what I sometimes think – is mowing their lawn.
It just looks so beautiful and neat when the lawn was mowed and it also smells so fresh.
Unfortunately, this practice also is harmful to many animals.
Mowing often prevents the flowering of clover and other plants and grasses. Their flowers could be a healthy food source for many insects.
In addition, the lawnmower always injures or kills many animals directly, if they can not escape fast enough to safety.
It might be important in certain places to keep the lawn short.
For example, next to the vegetable beds, where otherwise slugs and snails could hide during daytime, and easily invade the beds at night.
But that is not important in other areas of the garden.
Hence it is beneficial to many animals to leave some areas of the lawn alone and maybe only mow them two or three times a year.
Also many enemies of slugs and snails would benefit.
In these areas the native plants can flower and give food to many species.
Especially the kind of meadows, where only two or maybe three times a year hay is made, offers food and a perfect habitat to countless plants and animals.
Abstain from chemical crop protection
There is nothing worse for the biodiversity than environmental toxins.
They are used in many places to “protect” one sort of plants or animals but at the same time they kill a whole lot of others.
Often, users are unaware of the huge damage they are doing by using sometimes called “harmless” insecticides or herbicides.
Unfortunately, many poisons are still permitted which damage our plant and animal life to an extent that we cannot yet foresee.
By using poisons that accumulate in nature (eg. neonicotinoids), countless species are already completely extinct or threatened with extinction.
This is one of the main reasons slug and snail problems are affecting many gardens year after year.
The fact that many insects are already extinct, makes it possible for mollusks to multiply and spread so rapidly.
A species once lost can never be brought back. Therefore, it is invaluable to relearn to cultivate the garden without modern age poisons.
There are many ways and means which can help to promote a species-rich habitats. The above mentioned ones are just a few of them.
Basically, it helps to garden a bit less meticulously and to offer many sites that could become a safe dwelling for all forms of wildlife.
Dry stone and wood piles, garden ponds, deadwood and hedges can do their part to protect mother earth and many of its species.
This allows nature to recover slowly and natural balances can be restored.
And if the enemies of the slugs again find enough niches in the garden where they can settle, the snail and slug populations will naturally be kept small.
In addition also many other sorts of animal pests will be nipped in the bud.
Further methods to control slugs and snails
slug fences (soon)