The caravan site beside the loch in Ullapool has midge machines dotted around the site, which collects millions of the blighters. Caravanning on the west coast in the midge season can be a miserable experience on still days. One of the worst places we've personally experienced them was a few years ago at the Forestry Commission site at Loch Rannoch - a beautiful area, but on still, damp days, when the sun comes out, clouds of them descend to eat you alive. The site takes tents too and unsuspecting campers pitching tents beside long grass and near water, are soon jumping around, smacking arms, legs and faces. A walk to the toilet block is a mad dash with hoods up and hands hidden up in sleeves!
Avon Skin so Soft works very well and some shops in the highlands stock it. We now order ours online, before we travel. By the way, if you or your children get bitten and you don't have anything to hand, a dab of toothpaste (which you are more than likely to have in the caravan or tent), on the bite really works. They use this for insect bites in the Far East. I used it on a mossie bite last week and didn't need to put anything else on it.
We love Scotland, but only go now before the midge season starts.