Eeeuuuuwww! I hate mice!!! I had them bad a few years ago. First of all, they have to be coming in from outside somewhere. I called an exterminator in who told me mice are very agile and can squish themselves down to where they can get in a space less than an inch wide. So make sure you've got weather stripping on all doors at the bottom and check your garage door stripping too. Mine actually got in from my dryer. The hose had a tear in it and the little rodents came in that way.
They made themselves right at home and before I even realized they were co-existing in my house, we were INFESTED!! Now my dad told me, "Don't go beserk-it doesn't take very many of them to make a heck of a mess." So here's what he told me to do:
Go to the hardware store and buy some of these cakes-the store clerk should know what they are. It causes the mice to die of dehydration. And get some D-con too. D-con is awesome. Put it where you found the droppings. They'll eat it and croak somewhere. One died under my stove. I found it 2 years later! Eek. If you have little kids, don't use the cakes or D-con if it's where your kids can get to it. That blue D-con is very attractive to kids. And both are highly toxic. Fortunately, I put mine under our house in the crawl space and it had a locking door so my kids were safe.
Also, consider getting some traps. I preferred the metal live traps. Peanut butter is a good bait. Also good bait is dog food, cat food, rabbit food, hamster food etc. My exterminator told me too, to take some floss and cotton and wrap it around the holes with a tiny bit sticking out of the trap, tie it so they can't undo it. This should attract the mice into the trap. They might be looking for nesting materials and this will entice them into the trap too.
I was unknowingly feeding our critters with a door stop I made and had stuffed with rice. I had stored it in a closet and they ripped it open and were feasting on it. So mine were well fed and didn't go into the traps unless I forced them. And yes, there were nights when you could find me with tons of cardboard boxes laid out (my own stupid traps), a broom in one had and a plunger in the other. Yeah, I know. Nuts. I caught two that way, by hunting them down and chasing them into the traps.
Also good but expensive are the electronic traps that you get at Kmart or such stores. They have a light that changes color when a mouse goes in. When they're in there, a tiny bit of electric charge kills them. There are also snap traps you can get that are covered where you don't have to see the mice if you're squeamish. I got some of those for outside.
Also, keep in mind, mice are super curious and are interested in traps. Put them (if you use them) along walls. Mice rarely ever venture out into open areas. They hug the walls when they walk or run. So put them in their path.
And my exterminator told me too, that if you think the mice are coming from a certain room-don't block it off. They might be out in the house hiding somewhere. You want to give them acces to their nests, because at some point they'll return there. This was hard for me. I knew they were coming from my crawl space and I couldn't block it off b/c I didn't want them to nest somewhere else. Kind of gives you the upper hand since you know where they were coming from!
I hope this helps. Not to scare you, but it took me 6 months to get rid of them. What finally worked was the D-con. I could tell it was working-once you see the green droppings you know they ingested it and it won't be long. There are tons of options out there and now that you've read my "book," I'll end this. If you have any questions, pm me and I'll try to help. I feel for you-mice are an icky experience. Mine climbed closet walls, pooped on clothes, scratched coats all up, ruined stuffed animals, peed all over the floor, chewed up my mattresses.
Oh, also, clean under couches! My DH was a popcorn monster and when he ate it, he would drop a lot of it under the couch. The mice pushed it all up in a big pile and were eating it. My kids dropped food all over too-make sure all crumbs are picked up-they feed on that stuff. I put all my food up high (they can get in cupboards too). Good luck!!!
