I'm lucky enough to live in an area that does not have many slugs. For those of you that do contend with them, here's an idea.
Add slug bait. Place this bottle in the dirt where slugs are a problem. After you catch some slugs, you can either take it apart and clean it out or just toss the whole thing and start over.
An iron phosphate product like Sluggo is the best slug bait to use. It is not toxic to people or pets.
Here's a link to all of my pest control pages on my website.