Slug

The common name no doubt refers to their very slow locomotion and/or appearance. Slugs are a nuisance pest indoors, but outside they cause severe damage to flowers, garden plants, and fruit trees. Various species are distributed throughout most of the United States.

Recognition

Adults are about 1-8 inches long. Body soft, lacks segmentation, jointed appendages, exoskeleton, and a backbone; with one pair of conspicuous upper tentacles usually bearing eyes near their tip and one pair of short tentacles beneath on head end. Color various, usually rather dull brown or gray, sometimes with darker markings; some species brightly colored, being green, yellow, etc. Mantle confined centrally to anterior half, or covering complete dorsum; without a shell. Back with or without a keel of various lengths. Foot with mucus glands; move by gliding on a mucus film. Nocturnal.

Habits

Slugs spend the day in sheltered, damp places such as under decaying boards, landscape timbers, logs, and stones, under board walks and low decks, in damp refuse and litter, under low-lying and dense vegetation, in damp crawlspaces and basements, in spring houses, etc. Ivy bends are a favorite refuge. Occasionally, they can be seen in the early morning if the area received rain or was watered, and/or in the early evening on dark, cloudy days, especially in moist, shaded areas. A drop in temperature and rise in relative humidity usually causes slugs to become more active.

Wherever they go, slugs leave a slime trail that may remain visible for days. Their trails avoid dry or dusty areas and sharp objects. Many species often will follow or use the same trail day after day. When accidentally crushed underfoot, they cause an unsightly and odorous mess; some people find this very stressful.