The size of this slug varies, they occasionally reach dimensions of about 25cm at maturity, but usually are under 15cm. The color of this slug is generally black, as its name suggests, but the coloration is quite variable, and it can even be white! Young specimens are brown in color, which gradually change as they reach their mature state.
The black garden slug covers itself in thick, foul-tasting mucus, which serves as both protection against predators, as well as a means to keep moist. It is somewhat difficult to wash off your feet, so watch where you walk!
This species is well established in the Pacific Northwest region and is considered a potentially serious threat as a pest, it is an invasive species which can negatively impact agriculture. They are originally out of Europe but are now invasive in other countries, they are becoming a serious threat in Canada.
Black garden slug is originally from western and central Europe, they have been introduced into many countries worldwide. Black garden slugs have been found in BC since 1941 and have been considered a serious pest since the early 60s. Black garden slugs are the most common slugs in southern British Columbia now.
Like all other species of the gastropod family, the black slug can fertilize itself if needed, although a mate is preferred. After mating, the slug lays eggs of about 5 mm in diameter.
This black slug is mainly nocturnal and avoids exposure to sunlight. It is omnivorous, eating carrion, fungi, and vegetation – living & decaying. The slug prefers moist conditions, such as lawns, making it an unwelcome sight for homeowners.
In spite of the slug’s mucus being highly distasteful to many animals, it does have some natural predators, including shrews, toads, snakes, and a few birds.