Class: Gastropoda, Unknown group.
Slugs are legless, soft-bodied creatures that resemble snails without a shell. A number of species of slugs are found in Wisconsin, but gray and spotted garden slugs are the most common.
Slugs thrive under cool, damp conditions. Slug populations will be high during and following damp, rainy weather, and will almost disappear during dry periods. Slugs cannot survive direct sunlight, and without protective hiding places during the day, they rapidly lose body moisture and die. Rock walls, boards, pots and plant debris, as well as shaded flower beds and heavily mulched gardens, serve as ideal daytime resting sites.
These were under a log in the grass during the day. The slug likes it under things like a log were its cool and damp.