The Latin name for this creature is Limax maximus, which literally means “biggest slug.” It is also known by the common name Great Grey Slug. Although I occasionally see them in my home state of Ohio, I saw quite a few while visiting southern Illinois.
Adults measure 4 to 8 inches in length and are usually a light grey or grey-brown with darker spots and blotches, although their coloration and patterning is quite variable. Although native to Europe, this species has been accidentally introduced to many other parts of the world.
It makes its home in forests, but is often also found in cellars and in cultivated areas. Leopard Slugs are mainly active at night, though they may also be seen in daytime during wet, warm and overcast weather. During the day they hide under stones, logs and in dark wall crevices.
Leopard Slugs don’t tend damage living plants, but instead eat other slugs, including species that can damage garden plants and vegetables. They also eat dead and rotting plants along with fungi and this recycles nutrients and fertilizes the soil.
All slugs are slimy, but this species is especially so, giving it a highly unappealing and defense against predators.