The common garden slug breeds throughout much of the year and can be a serious pest of gardens as they attack cultivated plants, fruit, tubers and bulbs (1), which are eaten by means of a rasping tongue known as a radula. They emerge at night, and spend the day in moist places beneath stones, logs and other objects (1).
Slugs are related to snails; in the genus Arion, the shell is reduced to a group of calcareous granules below the 'mantle', which appears as a bulge on the upper surface of the slug (3).
Slugs are hermaphrodites, meaning that individuals possess both male and female reproductive organs, but self-fertilisation does not occur. During courtship, members of a pair follow each other in circles, whilst feeding on their partner's mucus trail (3).