Wired! Insect deterrents

[Thomas Schley]

Hi Folks,
An acquaintance told me she's heard of people using very thin copper 
or silver wire to ward off insects and maybe other critters.  The 
wire is strung a few inches above the ground and runs up and down the 
garden rows.  Anyone heard of this?  What is the principle behind it? 
I assume it concentrates energy somehow that insects don't like. 
Since it doesn't seem to be very common it must have some drawbacks? 
Or is it just one of those magnificent ideas from the 1960s like 
smoking banana peels?
-Tom