billy_bunter wrote in message . ..
Peter H.M. Brooks took the time to write...:


Try ANTI-MAL, a free PC program that emits a very high (supposedly
inaudible) tone that is variable to repel the little buggers...
http://www.thaiware.com/software/util/UL00724.htm

I gather, from research I have read, that ultrasound doesn't bother
mosquitos, nor, for that matter, mice, rats or moles. I remember
reading about that program, I doubt it would work as most speakers are
designed to produce sound that is in the audible range so won't do
very well in the inaudible range - and, as you are suggesting, there
are likely to be audible harmonics.