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Hardly any other insect repellent separates the ghosts like slug pellets. The molluscicide is said not only to be deadly to snails, but also to be toxic to mammals, especially hedgehogs, dogs and cats. People, especially small children, are said to be poisoned by slug pellets and even be fatal if the amounts are too high. However, not every product that goes under this name is the same and the different ingredients have different effects on organisms.

slug pellets

What is slug pellets?

Slug pellets are molluscicides (chemicals used to repel molluscs) that are spread around the garden and eaten or touched by the slugs. After the snail has ingested the remedy, the active ingredients move into the organism and let it die. The composition of the slug pellets is designed in such a way that the molluscs are strongly attracted to it and literally flock around it. But here the problem arises. Snails are readily eaten by other mammals and birds, which then absorb the drug into their digestive tract. Depending on the active ingredient, this ends fatally, so the two main active ingredients must be compared.

  • ferric phosphate
  • metaldehyde
Insect repellent slug pellets

The agent is mainly obtained from these two substances and then processed into small balls, a granulate, as it remains in the soil of the vegetable patch for a long period of time. Depending on the active ingredient, however, this must be redistributed as it can be washed away by the rain.

ferric phosphate

Ferric phosphate is a chemical compound that occurs in nature, for example as the mineral strengite. It is also released from fertilizers containing phosphate as soon as they come into contact with water. Ferric phosphate is obtained from iron in reaction with other substances, such as phosphoric acid, and is harmless to mammals and birds. Even when consuming large amounts of slug pellets, which are based on iron-III-phosphate, there are no negative effects on dogs, cats or humans, and even small children do not suffer from them. Nevertheless, there is of course a risk of suffocation if children put the grain in their mouths.

The following manufacturers offer iron-III-phosphate-containing products:

  • Biomol from Bayer Garden
  • Ferramol von Neudorff

mode of action

Iron-III-phosphate has a toxic effect on the snails and ensures a so-called feeding stop, which stops the animals from eating the lettuce. As soon as the snail has consumed enough of the preparation, it withdraws into its burrow and dies there. It does not slime and no longer poses a threat to birds, hedgehogs or other creatures.

Snail on a plant leaf

Other advantages are:

  • environmentally friendly
  • non-toxic to bees, ground beetles and other beneficial insects in the garden
  • does not affect the quality of the crop
  • rainproof

Depending on the manufacturer, there are different compositions of the active ingredient, but they basically have the same effect. A great advantage of slug pellets is the possibility of using them throughout the season, since the phosphate does not have a negative effect on the soil quality and thus on the plants. You don't have to collect dead snails yourself, they are decomposed by natural processes in their shelter and are therefore easily removed from the way. What is particularly important here is the distribution in the spring, before the snails can reproduce.

Notice: Unlike metaldehyde, ferric phosphate is approved for organic farming and horticulture. That means you don't have to worry about your plants or pets if you want to stop snail eating.


Metaldehyde is the real culprit for the widely asked question of whether slug pellets are really toxic. Metaldehyde is derived from sulfuric acid and is highly flammable, killing snails within minutes. It is therefore also used as fuel when camping (Esbit). But the substance is not only toxic to snails. Small mammals such as hedgehogs or domestic cats and birds can suffer from symptoms of poisoning even in small quantities and then lead to death. This can also be observed in humans and, depending on the organism, there are different doses that are fatal.

  • adult people: 4 g (about one Esbit tablet)
  • toddlers: 2g
  • Dogs: 0.2 g to 0.6 g depending on the breed
  • cats: 0.2g
  • Small animals and rodents: 0.1 to 0.2g

mode of action

A long-term effect is more likely to be seen in birds, while the remedy works immediately in mammals. Snails begin to mucus a few minutes after ingestion. After only 20 minutes the snail is dead and you have to collect it one by one so that other animals don't eat it. The symptoms of metaldehyde poisoning include dizziness, visual disturbances, irritated mucous membranes, the onset of convulsions, respiratory distress, coma and finally death. Depending on whether the poison reaches the digestive tract, this happens in a period of 15 minutes to 24 hours.

apply slug pellets

Metaldehyde has the following properties:

  • deforms when it rains
  • can be washed away
  • kills snails instantly
  • tastes slightly sweet, therefore interesting for children and animals
  • particularly bad if distributed incorrectly in the garden
  • Waiting time before harvest, otherwise poisonous

For the above reasons, slug pellets based on metaldehyde should not be used, as this causes more damage. Although the snails die off immediately and cannot cause any further damage, the risk of small children or pets accidentally coming into contact with the agent is too great. Because of the flavorings, children in particular may mistake the granules for candy or something similar.

Notice: Slug pellets got such a bad rap because of a witness account of a deceased hedgehog that ate a slug that had previously ingested metaldehyde. The extremely large amount that the hedgehog ate was the result of incorrect distribution by the user, who offered the slug pellets in a rain-protected container.

Useful snails

Harmful to beneficial snails

Many gardeners consider snails to be harmful in the garden, but few people know that there are also beneficial insects in the form of snails. These take systematic action against the harmful snails and either kill them directly or feed on their eggs. There are also numerous types of snails in the garden that are not at all interested in vegetables or fruit and eat other food.

  • Slugs (Limacidae)
  • Banded snails (Cepaea)
  • Roman snail (Helix pomatia): is under protection

The tiger slug in particular is a welcome guest in the garden, as it specifically hunts the slugs that attack the plants.

Roman snail in the bed

These are:

  • Spanish slug (Arion lusitanicus)
  • field slug (Deroceras reticulatum)
  • Garden slug (Arion distinctus)

The pests are mainly recognizable because they do not own a house. Except for the edible snail and ribbon snail, the tiger leg also has no shell, but it can be recognized by the characteristic color that gave it its name. While slugs are predatory, edible snails and ribbon snails eat rotting plant matter and the pests' eggs. Therefore, they are also very helpful in the garden. For this reason, general use of slug pellets is not recommended when there are many of the other slug species in your garden. Therefore, only use slug pellets if there is a really big plague.


If slug pellets seem too dangerous or toxic to you in general, there are a variety of alternative home remedies that are much gentler. Although ferric phosphate is not toxic or harmful, it can greatly reduce the number of beneficial organisms because the grain is never selective.

Slug pellets can cause symptoms of poisoning

Try the following alternatives:

  • Introduce predators: hedgehogs, fireflies, shrews, lizards, frogs, chickens, pheasants, turtles and more
  • Introduce predatory snails
  • scarify
  • Avoid lawn mulch as snails thrive there
  • Set up a beer trap
  • Build a snail collar and fence
  • Spray plants with a solution of liverwort extract and water, as snails strongly avoid this solution
  • Lay out cocoa shells
  • collect by hand, especially in spring

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