I had this problem and thought the solution sounded crazy but it works! And greatest of all is non-toxic to us!! Take a small flat bowl or plate with lip around it.....ao they can get in it but not "fall" in it or they will be scared to go by it or try to get in. Put some block cheese in it....like a chunk Then put in some table salt, white vinegar and dawn dish soap. Stir it a little to get the salt to disolve. Leave it in the area you dont want the mice. When they eat it it will kill them. The gross part is that they will die right away so you may have to pick up and throw away dead mice
This also works on creeping charley! If you have this problem and boy I did...you know that NO product out there kills it. So you mix this:
2 cups table salt
1 gal white vinegar
8 drops dan dish soap
stir it a little to get the salt to disolve
put this in a spray bottle and spray the creeping charley. It will kill any grass underneath it though so you have to "re-grass" the area.