I speak from experience. My flat isn't ghetto, but yet still there is a mouse (or mice) who had found its way into our kitchen. Ok, could be worse...and it fact it is.
This has happened 3 or 4 times where I wake up to a scratching noise from inside the ceiling above my bed. Mind you, the vaulted ceiling is very low here in my room, so this mouse is literally separated by 1" of drywall from landing on my sleeping face. Shudder. As usual, find a graph best describes my situation.
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I'm too scared to plant mouse traps, and have no real idea how I could catch one inside a wall anyway (our food is secure, so it's coming in from outside).
Completely irrelevant side note: anyone interested in visiting me and staying at my humble abode :)