Only
really a pain on the West coast Michael, although the little buggers also fly East to annoy us !! They like damp, windless conditions (hence the West coast) so avoid rivers and under trees etc... You will encounter them in full force on Skye at Talisker - I have known people to go mad with scratching at Loch Coruisk, Glen Brittle and Sligachan.
There are many proprietary lotions and potions to buy and fend them off. One of the better ones is
Jungle Formula which contains DET or DEET (diethyl toluamide) This is a fairly foul smelling chemical - do not get on your lips as it has a numbing effect !!
Another product, allegedly used by our Marines on active duty, is
Skin so Soft by Avon. Smells nice and moisturises the skin and does seem to have a positive benefit.
My experiences are that they prefer females to males, probably because they are less hairy and the skin is softer. I have this personal theory that it is also due to oestrogen levels and pheromones - females usually smell nicer than males so avoid perfumes and after shaves etc..
Finally, I think that it is only the female, pregnant midge that bites and gets blood to support the young. However, I stand to be corrected on that one.
I'm sure JohnW is probably a midge expert and has some other ideas - a 15% solution of donkey shite and seawater, cow muck and joghurt etc..... Cue John
Further info. on the little bastards
http://www.albawest.com/midges.html#Chemical