What Substances Are Used in Slug Pellets and Slug Baits?
Slug pellets and baits contain molluscicides, which are poisonous substances that kill all slugs and snails. They also contain attractants that make slugs and snails eat the pellets.
These attractants are powerful; that is why slugs and snails prefer eating the pellets instead of plants.
At least for a short time, the plants are safe.
In the long run, however, pellets cause a lot of harm. They fight only the symptoms, but not the causes of the problem.
Apart from the poison, manufacturers do not need to indicate what other chemicals they use in the baits.
Be aware that by using pellets you are putting chemicals in your garden, and they might end up on your table and in your food.
What Are Slug Poisons – Active Ingredients?
Slug pellets contain three main types of poison – iron(III) phosphate, metaldehyde, and methiocarb. Each acts quite differently and has distinct advantages and disadvantages.
Some pellets are even lethal to humans and can pollute groundwater.
Methiocarb and metaldehyde can be fatal to humans and pets. If poisoning is suspected, contact a doctor and call an ambulance immediately!
Iron(III) Phosphate
The most common snail and slug poison is iron phosphate / ferric phosphate.
At first glance, it seems harmless and is even approved for use in organic farming.
How Does Iron (III) Phosphate Work?
After snails or slugs have eaten the poisoned baits, the iron blocks their throat and closes down their digestive tract.
As a result, they can no longer eat and slowly starve to death. It usually takes a few days for them to die.
Beneficial snails die if they eat slug pellets.
After eating the baits, snails and slugs find a place in which to hide, and they die unnoticed.
As they are not killed immediately, there is the risk that they will reproduce before they die!
Dead slugs and snails cannot be collected because their bodies are hidden from view.
The bodies release a smell of decay into the garden, and this attracts even more slugs from around the neighborhood.
Although allowed in organic farming, iron (III) phosphate is a hazardous chemical substance that is not entirely harmless to humans.
After coming into contact with the pellets, you should wash your hands thoroughly.
This substance can also pollute drinking water, so it must not enter drains, surface water or groundwater supplies.
Metaldehyde
Metaldehyde can be deadly to humans and animals, and it pollutes groundwater.
However, its use is still permitted in the garden and in agriculture.
Metaldehyde is a contact poison.
After slugs and snails have eaten or touched metaldehyde pellets, their bodies produce excessive amounts of slime, and they slowly dehydrate as they try to flush the toxin out of their system.
As a result, they die from internal water loss.
If it has been raining or the ground is very moist, metaldehyde can become ineffective, as the slugs can take in enough water to compensate for their losses.
After slugs and snails have died, their bodies lie scattered around the garden.
They must then be collected; otherwise, their smell will attract new slugs from around the neighborhood.
Metaldehyde was found in groundwater all around the UK because it is used a lot in agriculture.
This might also be true for North America and other parts of the world, and it might have an effect on general health.
This is why some people advocate for the prohibition of metaldehyde.
Used a lot during the 1990s, methiocarb has now been banned in most countries because it is fatal to humans and kills many beneficial animals and pets.
Dogs, especially, like to eat methiocarb pellets and they can die quickly.
Beneficial earthworms also suffer a lot.
Old stocks of methiocarb slug pellets should be disposed of properly.
Not only do all slug baits carry poisons, but they are also powerful attractants.
That makes them a double-edged sword.
They attract slugs and snails from around the neighborhood into your garden, and directly onto the vulnerable beds where you are meant to sprinkle them.
Slug pellets dissolve over time and in wet conditions they start to go moldy.
The attractants that are not eaten can seep into the soil and will attract slugs and snails even after the baits become invisible.
Many people underestimate the fact that the smell of carrion is a strong attractant to most snails and slugs.
Therefore, slug pellets directly – because they contain baits – and indirectly – because they produce carrion – attract even more slugs from neighboring areas.
If it is true that slugs can smell (e.g., beer) at a distance of over 150 yards (140 meters), this effect might reinforce the slug boom in your yard.
Please be aware of this risk!
Dogs can die after eating slug pellets.
They are Poisonous to Pets and Humans
Slug pellets contain poisons that can also be dangerous to mammals.
Metaldehyde can kill pets such as cats, rabbits, ducks, and dogs.
It also poses a health risk to toddlers, babies, and children in general.
Even for adults, certain doses can be fatal.
The toxicity of slug pellets should never be underestimated.
Less than an ounce (just a few grams) of metaldehyde is enough to kill a human being.
Dogs and cats have been known to die after ingesting slug pellets.
Dogs, especially, like to eat the pellets; a lethal dose for them is only about 1/30 ounce (1 gram) of metaldehyde.
If you suspect poisoning in babies, children, or pets, seek medical advice immediately.
Severe poisoning caused by slug pellets has even been reported in cattle and horses.
Symptoms include breathing difficulties, vomiting, lack of coordination, cramps, and fever.
A slug has laid its eggs.
Enforced Reproduction and Propagation of Slugs
One significant setback of iron phosphate pellets is that they kill slugs and snails slowly within a couple of days.
During this period, the slugs and snails stop eating, but can still mate and lay eggs.
As a result, the natural cycle of reproduction is disturbed, which leads to an out-of-the-ordinary slug boom a few weeks after using the pellets.
For every slug killed, 300 to 400 new ones could hatch.
This leads to a slug ‘revenge’.
Hedgehogs, for example, suffer from the use of slug pellets.
Natural Enemies of Slugs Suffer
Some people say that invasive slugs and snails have no natural enemies.
However, this is not the case in most places.
Slugs and snails inhabit most of the world and have many natural enemies.
Their eggs, young, and even adult slugs and snails are on the menu of all kinds of predatory animals.
However, it is true that natural enemies have declined in population or have become extinct for several reasons.
Often, they have suffered from the use of pesticides such as insecticides, herbicides, and molluscicides.
Sheep wool pellets as protection against snails & slugs
These animals like the protein-rich meal provided by a slug, a snail, and their eggs.
If invasive slugs or snails enter an ecosystem for the first time, it might take a while for the snail eaters to recognize them as a potential snack – but after a while, they will.
If these animals eat poisoned slugs or snails, they might get injured, too.
And if they do not die, they might feel sick and avoid touching a snail afterward.
Slug pellets counteract natural checks and balances.
The Restoration of a Natural Equilibrium Is Prevented
If you use slug pellets, the restoration of natural checks and balances will be prevented.
The use of poison sets a vicious circle in motion: ‘Harm set, harm get’.
When poison is used to kill a prey population, the balances that exist between hunter and prey populations everywhere in nature cannot occur.
There are, for example, many insects, such as ground beetles, that specialize in hunting slugs and snails.
If all slugs die suddenly, these animals lose their food supply and move to other areas.
If they are dependent on snails and slugs, as glowworms are, they could even starve to death.
As a result, the next generation of slugs can boom because it will face fewer natural enemies.
Beneficial snails and slugs – such as the leopard slug – die from slug pellets.
Beneficial/Native Slugs and Snails Die
Another big problem is that slug pellets kill all slugs and snails.
Not only will invasive slugs (such as the Spanish slug) die but endangered native species will too.
Most slugs and snails are beneficial to the ecosystem and are not usually a threat to healthy plants.
They eat dead animals, fungi and old plant remains. In this way, they are beneficial for plant growth.
By recycling garden waste and producing useful humus, they increase soil health.
As a natural part of the ecological system, native snails and slugs do not multiply explosively, as can happen with invasive species.
From my point of view, slugs and snails deserve respect, too.
They are part of life and usually make a helpful contribution by processing dead plants and carrion.
If you take a closer look at slugs and snails – and for a short time forget all the trouble they might cause – it becomes obvious what marvelous creatures they are.
They deserve respect for what they do and for the way they live.
To me, they are little Zen masters, and by observing them closely, it is possible to learn a lot about patience and tranquility.
Maybe that is why they appear to be under nature’s special protection, and why most of the time and in most places it is impossible to win an aggressive fight against them.
Fortunately, the use of poison is unnecessary; there is already enough know-how to protect vulnerable plants more peacefully.
Reverence for life can be preserved in the garden. There are many natural slug control alternatives.
Alternatives to Slug Pellets
There are environmentally friendly measures that can solve the slug problem.
5 thoughts on “Slug Pellets and Baits: How Do They Work? | Dangers, Risks, and Pet-friendly Alternatives”
You have definitely changed my perspective on my use of pellets! I am a new gardener who lives on the banks of a huge river, and I have taken to using a spray bottle with ammonia and water to kill them. I ho out about twice a week after dark and after sprinkler time and kill every snail & slug I see. I have often wondered if they can feel, because this looks like a terrible way to die. Going out tomorrow to buy copper mesh to try instead. Additionally, upside down Slurpee cup lids and many kinds of fast food clear plastic cups work great recycled as garden cloches. Another great idea, thank you.
I have a Composting Bin which contains compost and many slugs and worms. I wanted to know whether the worms would be affected by the use of Slug pellets. This article has clearly demonstrated that the worms will be affected and the use of natural slug removers is the preferred method. My composter seems to be a fantastic breeding site for earth worms, which may be because it has a lid and that excludes bird ‘predators’. My Brother purchased some worms to ‘start’ his compost heap, if I had known that he wanted some I am sure that I could have spared some from by compost bin. When we were young we would ‘find’ worms we called “Compost Worms” which have yellow / pale brown bands / stripes around their segments
Hi there, your list of slug predators did not contain the most prevalent predator in city areas – RATS! We had a rat plague in our area recently and it was the only time we haven’t been plagued by slugs in our garden. We dealt with the rats and now the slugs are back! I’ll take the slugs over the rats any day, though.
Hi. Fortunately Metalhedyde is now banned in the UK. I would never use it anyway. I have turned to Ferric slug pellets though, and collection/removal.
I’m starting to feel that my ‘close to natural’ approach has encouraged slug numbers. In the dry subtropical garden that I became previously accustomed to it’s so much easier. But in wet cool UK conditions slugs love all that wildlife friendly debris, cover and soil non-cultivation it seems.
This year a number of plants have had sections cut from well developed stems along a bed next to a neighbour’s path that they have woodchipped. So maybe that is harboring slugs. Even the blackbirds that are constantly searching the neighbours’ mulches are maybe not enough to control them.
But.. my reason for posting: If, as you say, beetles prefer poisoned slugs, there’s no reason that i can see that should affect slug numbers compared to no pellets. However, their consumption would remove the decaying corpses that you suggest may attract other slugs. Thus the beetles’ preference would seem to compliment pellet use rather than contra-indicate it. Also, the reduced energy barrier for beetles to eat slugs could result in greater slug predation by beetles, possible adaptation over generations to eating more slugs, and more energy for reproduction. Thus higher beetle numbers using behavioural ecology principles.
Bed barriers don’t look so convincing to me as plants grow and exceed bed boundaries as a matter of course, unless one wastes a lot of space or grows only compact plants. I used to use old milk bottles filled with water. I watched the slugs slide under the water and up and into the beds. Also they love sliding under plastic and hanging around water. Plant barriers/plastic bottles etc are usually helpful, in my experience. Except where slugs get inside or plants touch the tops where slugs love to slide over the plastic. Then they can be worse. With 95% of slugs underground there is always a fair chance of one coming up under the protection.
You have definitely changed my perspective on my use of pellets! I am a new gardener who lives on the banks of a huge river, and I have taken to using a spray bottle with ammonia and water to kill them. I ho out about twice a week after dark and after sprinkler time and kill every snail & slug I see.
I have often wondered if they can feel, because this looks like a terrible way to die.
Going out tomorrow to buy copper mesh to try instead. Additionally, upside down Slurpee cup lids and many kinds of fast food clear plastic cups work great recycled as garden cloches. Another great idea, thank you.
I have a Composting Bin which contains compost and many slugs and worms. I wanted to know whether the worms would be affected by the use of Slug pellets. This article has clearly demonstrated that the worms will be affected and the use of natural slug removers is the preferred method. My composter seems to be a fantastic breeding site for earth worms, which may be because it has a lid and that excludes bird ‘predators’. My Brother purchased some worms to ‘start’ his compost heap, if I had known that he wanted some I am sure that I could have spared some from by compost bin. When we were young we would ‘find’ worms we called “Compost Worms” which have yellow / pale brown bands / stripes around their segments
Hi there, your list of slug predators did not contain the most prevalent predator in city areas – RATS!
We had a rat plague in our area recently and it was the only time we haven’t been plagued by slugs in our garden. We dealt with the rats and now the slugs are back! I’ll take the slugs over the rats any day, though.
Hi. Fortunately Metalhedyde is now banned in the UK. I would never use it anyway. I have turned to Ferric slug pellets though, and collection/removal.
I’m starting to feel that my ‘close to natural’ approach has encouraged slug numbers. In the dry subtropical garden that I became previously accustomed to it’s so much easier. But in wet cool UK conditions slugs love all that wildlife friendly debris, cover and soil non-cultivation it seems.
This year a number of plants have had sections cut from well developed stems along a bed next to a neighbour’s path that they have woodchipped. So maybe that is harboring slugs. Even the blackbirds that are constantly searching the neighbours’ mulches are maybe not enough to control them.
But.. my reason for posting: If, as you say, beetles prefer poisoned slugs, there’s no reason that i can see that should affect slug numbers compared to no pellets. However, their consumption would remove the decaying corpses that you suggest may attract other slugs. Thus the beetles’ preference would seem to compliment pellet use rather than contra-indicate it.
Also, the reduced energy barrier for beetles to eat slugs could result in greater slug predation by beetles, possible adaptation over generations to eating more slugs, and more energy for reproduction. Thus higher beetle numbers using behavioural ecology principles.
Bed barriers don’t look so convincing to me as plants grow and exceed bed boundaries as a matter of course, unless one wastes a lot of space or grows only compact plants. I used to use old milk bottles filled with water. I watched the slugs slide under the water and up and into the beds. Also they love sliding under plastic and hanging around water.
Plant barriers/plastic bottles etc are usually helpful, in my experience. Except where slugs get inside or plants touch the tops where slugs love to slide over the plastic. Then they can be worse. With 95% of slugs underground there is always a fair chance of one coming up under the protection.
I put slug pellets round my lettuce plants if I rinsed the lettuce leaves under running water for ages can it still poison adults