Nick, every few years I end up with a mouse population out around the garden. They climb up into my tomato plants and eat tomatos, the damage is very similar to tomato hornworm, except they don't eat any leaves, just tomatos. Point being, I put mouse traps around the garden in all the good places, plus I even put them up into the tomato plants that are getting mouse damage. I catch plenty of mice, but I have caught some pretty big slugs in mouse traps too! I had the same problem with disappearing bait, sometimes it's slick mouse, often times it's ants, but I never even considered slugs until I caught my first.