Slugs are not insects, but are legless mollusks, like snails without shells. Overwinter in the egg or adult stage, depending on the species. Juvenile slugs hatch from eggs as soon as soil warms in the spring. Each slug possesses both male and female organs, and produces clumps of 10-20 eggs laid in crevices in the soil, under debris, or other protected locations. Prefer dark, moist areas like under boards, rotting mulches, trash, etc. and feed at night. They feed by rasping the leaf tissue, leaving a ragged shredded appearance to the leaf. Slugs move on their bellies and leave a silver-colored slimy trail wherever they travel.
Slugs make ragged holes in leaves beginning with lower leaves. Leaves may appear shredded. Silvery slime trails are telltale signs of slugs or snails.
More of a problem in cool, wet weather. Several days of warm, sunny weather may reduce the problem. Toads, some beetles and their larvae, parasitic flies and birds are natural enemies of slugs, but are not very dependable.
Eliminate hiding places. Remove rotting boards and debris. Keep gardens weeded and grass cut short. Small pans or canning lids sunk into the ground and filled with a mixture of yeast and water may attract and drown slugs. Trap them by laying boards between garden rows and collect them in the morning.