主题：求灭鼠良策！！ -- 故园湾里

Mice can hear sound at a Ultrasonic frequency, which in inaudible to man. Based on this, a device can be built to repel mice from houses...

Check this out:

Mouse Mover: Ultrasonic Rodent Deterrent

http://www.sharperimage.com/us/en/search1/searchresults.jhtml?_DARGS=/us/en/include/standardheader1.jhtml.13

You don't have to buy at sharper image. Their stuff can be cute but pricy... Just google similar products online.

# Plug-in electronic device emits safe ultrasonic waves that drive away mice, rats, squirrels and other rodents — silently!

# Clean and odorless — no noxious poisons, messy traps or dangerous chemicals.

# Ultrasonic waves are inaudible to humans. Unit can be set so it won't bother non-rodent pets such as dogs, cats and birds.

# Two built-in speakers emit constant or ever-changing frequencies that rodents cannot get used to — so they leave!