Snails initially cause superficial damage to root tips, leaves and flower buds with their rasping tongues. Further feeding activity results in small holes. On larger, thicker leaves, almost exclusively the underside is eaten. These feeding sites can later scar and, as the plants continue to grow, distinct, extensive cork formations sometimes develop there.
The roots are often gnawed away near the root tip. The feeding activity on the roots causes wounds, which in turn often leads to secondary infestation with weak parasites.
Another sign of snail infestation is the sometimes heavy traces of slime and irregular-looking black faecal spots at the feeding sites.

The number of species of land snails can currently only be estimated, but it is thought to be over 25,000 worldwide. If marine and freshwater snails are included, the number rises to over 100,000. Depending on the species, their diet may be limited to plants, but it may also include small organisms, carrion and decaying plant matter. Herbivores have a multitude of uniform rasping teeth with which they can scrape off plant material.
Small water snails move around using a carpet of cilia, while others usually use a carpet of mucus. Even though the mucus moves in waves beneath the snail and is used multiple times, the snail's movement is very material- and energy-intensive.

Propagation

Even though snails are hermaphrodites (male and female in one animal), one animal takes on the female role during mating and the other the male role. After mating, the two snails remain connected and exchange a packet of sperm, known as a spermatophore. The sperm cells contained therein are stored in the snail's genital tract in the fertilisation pouch. The gonad (which also produces sperm cells and is therefore referred to as a hermaphroditic gland) produces the egg cells, which are fertilised with the stored sperm cells. As they travel through the oviduct to the genital opening, the fertilised egg cells develop into eggs, which are deposited in a special laying cavity or on parts of plants.

Treatment with slug pellets is carried out by spreading them evenly (approx. 5 g/m²) in the evening hours directly between the plants. The slugs eat the bait and then crawl away to die, whereby the active ingredient (often iron III phosphate) is converted into nutrients, making it safer for beneficial organisms. Reapply if necessary and lightly water dry soil so that the pellets swell and become more attractive.

Not all of these options are suitable for use on windowsills or in greenhouses; hedgehogs like their freedom, and shrews are not the most pleasant housemates either... but for the sake of completeness, they should be mentioned here.

Methods of biological snail control:

Natural enemies:
Predators: Create habitats for hedgehogs, shrews, slow worms and ground beetles, which eat snails.
Use nematodes: Use microscopic threadworms (e.g. Phasmarhabditis hermaphrodita), which parasitise and kill snails in the soil.

Bait traps:
Beer traps: Buried bowls filled with beer attract snails, which drown in them.
Polenta traps: Pots filled with polenta corn attract snails, which cannot tolerate the flour.
Bait stations: Provide hiding places filled with cat food and wheat bran and collect them.

Erecting barriers:
Copper tape: Copper reacts with the slime of the snail, which is unpleasant for them.
Sheep's wool: Placed around beds to deter snails.
Coffee grounds: Acts as a neurotoxin and has a rough surface.
Diatomaceous earth: Forms a dry barrier.

These treatment methods from 1848 are provided for informational and entertainment purposes only. Please note that the use of some of the chemicals mentioned here is no longer permitted today, as they can be harmful to health (including that of the user) and very harmful to the environment. Reading, reflecting and smiling are permitted, but do not attempt to replicate these methods.