Fairly large slug, up to 2 inches long, shiny, may be black, blue-black or brown. Tentacles colored like body. Underside yellow to orange.

An invasive pest from Europe, spreading through North America, as well as New Zealand. Often found in gardens, where it eats a wide variety of plants.

The shiny black body, and especially the brightly-colored sole, make this slug easy to identify. However, this is really a complex of three species (A. hortensis, A. distinctus, and A. owenii), which can only be told apart by examining their DNA in the lab, or by looking at their genitals under a microscope. All three are known invasives, so geography is no help..