http://www.allaboutslugs.com/eggshell-myth-busted/
All I did was search to see how small one had to crush them.
Would hate cutting a live creature into two.
I was given a few beer traps, they didn't work, and THEN I discovered you are supposed to dig a hole and put them in the ground ! Blow that.
I don;t have coffee grounds as I rarely have time to make the real McCoy. I have bags of beans I've yet to open and which have probably lost their flavour.
I have no fowl.
I may check out Eddie's suggestion, but FWIW QVC was pushing some expensive organic pellets this morning.