The message

from de_ja contains these words:

Hi,

I want to know if such devices as sonic repellers to deter mice and
rats and other rodents are actually effective.

For example the B&Q Rat & Mouse Repeller at

http://tinyurl.com/5a589b

Does anyone have any first hand experience of these devices, do they
really work?

Thanks very much for your opinions.

D

The little ones are toys. Expect to pay around £150 for a good
commercial one. Excellent within large exposed spaces like barns, lofts
and yards enclosed by stone walls. Virtually useless elsewhere.
Interesting effects on bats and would be completely illegal to use if
bats were present. I'm totally certain (! :-) ) t hat no-one here would
even think of using them in such circumstances.