Slug-damaged leaves on a hosta plant (Hosta sp.). Slugs are gastropod molluscs (like snails) that don't have a shell. They feed on a variety of plants, but hosta plants are a particular favourite. They are most active and night and when it is wet, and can do an immense amount of damage. They reproduce rapidly as they are hermaphrodites (every slug can produce and fertilise its own eggs as well as reproducing with another slug). Ways of controlling the damage from, and number of, slugs, include trapping them, poisoning them, and using biological controls such as hedgehogs.