Thank you for reaching out to ask2.extension.

If you have any old wood landscape Timbers, I would check them for rot.  Slugs love that kind of area.  Also wet leaf debris is another attractive home.

Here are some things I found on the U of M extension site.

- Diatomaceous earth (tiny fossilized skeletons of ancient aquatic diatoms) is coarse and can scratch up slugs. It is most effective when used in dry conditions and has little effect when it absorbs moisture. It is generally not an effective slug deterrent.
-Set out several flat boards, shingles or damp newspapers.. Check under these traps the next morning and kill any slugs that are hiding.  Repeat this step every night until the slug damage is no longer present.
-Set out several flat boards, shingles or damp newspapers.  Check under these traps the next morning and kill any slugs that are hiding.  Repeat this step every night until the slug damage is no longer present.

If you want more information and to read up on slugs, go to extension.umn.edu and search for slugs in the home garden.  There is also information on using beer as a trap.

Be sure to clear away all debris when cleaning up for winter.

Good luck!