The red slug (Arion rufus), also known as the large red slug, chocolate arion and European red slug, is a species of land slug in the family Arionidae, the roundback slugs.
This slug is distinguished from similar species by the position of its respiratory pore toward the front of its mantle, the lack of a keel on its back, and a wrinkled surface. It varies in color from orange or red to brown or black. The fringe of its foot is red-striped and its tentacles are dark. It is 7 to 14 centimeters long and its mucus is sticky.
The eggs are about half a centimeter long and are whitish when new, turning yellow-brown.
It is very similar to the black slug, A. ater. The two can be distinguished with certainty only by dissection or molecular analysis. It has been treated as a subspecies of A. ater in the past.
This species is probably native to northwestern Europe. Its distribution is unclear. It has been widely introduced and it is easily confused with other species.
It is known from wooded areas and dry coastal habitat, and is commonly found in gardens.
Like most other slug species, the red slug elongates while in locomotion, and at rest it contracts into a hemispherical shape. It performs a rocking motion when disturbed. It is an omnivore.
(latin: Arion rufus)
