There are many different kinds of slugs and snails. Terrestrial slugs and snails are a diverse and very successful animal group and most species move around unnoticed and function as decomposers in various ecosystems.

The slugs and snails that get most attention are the pests, which, in actually, are rather few species.

An infamous species is the Spanish slug (Arion vulgaris), also known as the killer slug. It is a serious pest, especially in gardens and parks.

Another serious pest in arable crops is the grey garden slug (Deroceras reticulatum), which causes significant damage to winter wheat and rapeseed. Changed cultivation practices along with climate change have improved conditions for the slug, and the grey garden slug in an increasing problem for agriculture.