These ultrasonic things are useless. This morning saw another mouse darting across my kitchen floor. If I wasn't barefoot at the time I would have stomped it.
Our neighbour, after Christmas, threw his tree in to his front garden for a few weeks, then transferred it to the boot of one of his (three) cars. Now? It's still there, all brown. Car hasn't turned a wheel in months. Really grating on me now.