Good point Colin... Dowsing is an "OLD CRAFT" that predates Ley Lines which was something made up by some bloke so he could write a book about it... found in the FICTION dept in most libraries!
This seem to be the problem... these lines of force or whatever they are have been dubbed Leylines.. which were lines of orientations that were man made or natural that appeared to line up... a typical nonsense pounce upon by those who are not gifted with so called supernatural powers.... nothing to do with Dowsing at all.
The lines that I detect with a couple of bits of bent wire when I think Bees do not seem to be electromagnetic, and do not follow overhead cables, in fact can run at angles to them with no apparent influence.
However, when Western Power could not find a live power cable running across my paddock, I managed to locate it exactly by dowsing, and the rods totally ignored lines that I knew intersected in an old oak where bees regularly swarm.
I have no explanation.... except perhaps there are anomalies in the Earths fields that bees navigate with, and orientate to.... that others can sense as well???
Yeghes da