Many years ago, we lived in a house where we saw a mouse scurry across the floor. Carol thought.... isn't that cute............. ahhhhhh.
Called a friend of mine that worked for an exterminator company and he said.... if you see one in your house, guaranteed there are many more behind the walls you can't see. We set some traps. Every trap had a dead mouse in them within a day or two. Turned out living in the city... when one person has them.... they live up and down the row homes and travel between them. Bugs do the same thing. I hated those mice. When we moved away... we cleaned everything very carefully before packing to make sure we didn't take any along with us.
Out in the country now... we get an occasional field mouse in the house, but we have the house and garage fumigated three times a year and with our two cats.... we have little to no problems. Our problems now are the turkeys and squirrels that destroy the property. The turkeys aren't bad, but I shoot the squirrels with a pellet gun and I'm pretty good at about 15 to 20 yards. We got rid of the groundhogs and most of the rabbits ourselves.
Those 'Have-A-Heart' traps are a bunch of crap. Set out to catch a raccoon and I catch opossums. Set a trap for a groundhog and I catch a skunk. I even put little signs on the cages explaining what the trap was for and these little scavengers still go in the wrong ones. Why can't they go where they're supposed to go like aspirin does in your body ??