Ha... I bought this for a mouse in the house ...and, caught so many gnats, flies, even a couple of baby geckos.
Aaaand, I caught the mouse....even one I didn't know I had.

Totally work, you just have to give it a little while.

Caught the little mouse that was scurrying in the basement, but only after months.
Edit: Eventually caught two more little mice that had fallen from the trap that was up high and I hadn't seen them. They had glue on them. Obviously, they got stuck on the edge of the trap and fell over the weeks.