You need to invest in some good, modern traps... not the cheap run-of-the-mill snap traps. I had the occasional mouse in my basement, and the wooden traps were very hit or miss; they'd steal all the peanut butter off of them. I bought some of the ones that they had to actually go inside and step on a platform to reach the peanut butter... they worked every time. Also, the ones where the peanut butter is kept inside a tray covered with the trigger work well. They have to stick their nose under the trigger and push it up to get to the bait... SNAP!
I've never missed a mouse with either of those two types of traps. The old style snap traps have gone into the trash.
First type:
The second type:
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