A couple cats should help the mice issue. I would recommend you try to get barn cats as youngish kittens, they'll be slightly ferrel & used to getting most of their own eats by caught goodies from mommakitty. But really it's 50/50...I have 2 cats, they'll both mess around with bugs, lizards, flies etc,& occasionally try for a bird, but they both punk out like lil b**ches & never finish the hunt with a kill, so we gotta try to watch their birding, we really don't give a damn about the bugs n flies, kill'em all. lol good luck-I hope you don't have to resort to the poison.