Slugs being the common name for the terrestrial gastropod mollusc, they are a fierce and lethal foe in your garden. They are able to cause an enormous amount of damage in your garden and greenhouse.
They will demolish leaves, roots, tubers, bulbs and buds, leaving a slimy residue behind. There are a number of species that attack the garden and unlike snails, they feed throughout the year. Feeding at night, they hide during the day under leaves, pots and sheds - any dark area.
The bodies of slugs are mostly made up of water, and with the lack of a full sized shell their soft bodies would soon dry up. To prevent this they must generate a protective mucus to survive. Many of the slug species are usually more active just after a rainfall because of the moisture in the ground. In drier conditions they will hide in damp conditions such as under tree bark, logs, rocks or man-made items like plant pots etc to help them retain theor body moisture.
Slugs produce two types of mucus, one is thin and watery and the second is thick and sticky. The thinner of the two spreads from the centre of the foot to the edges, the second thick mucus spreads from front to back of the slug. A thick mucus is aslo produced to coat the whole body of the animal.
To enable the slug to climb vertical surfaces without sliding back down, the slug's foot produces fibres which enables it to climb. This mucus trail or "slime trail" has secondary effects which both is a postivie and a negative for the slug. Other slugs that come accross the trail will follow it, some for mating but others for food! This mucus does offer some protection against predators as it can be distasteful and also hard to pick up.
Slugs are hermaphrodites, meaning they have both female and male reproductive organs Once a mate has been located they will encircle each other and sperm is exchanged through their protruded genitalia. A few days later the slug will lay approximately 30 eggs, deposited in a hole in the ground which is protected by some form of cover like a fallen log for example.
Apophallation is a common seen practice among many slugs. This is due to the large size of the penis that is wrapped around the body of the mate. As it will often become entangled the slugs will self-amputate by chewing the penis off to allow separation. Once done that slug will only have its female organs but is still able to mate.