Thanks for the replies so far..... although I now longer think "it's just us and our pool" (thanks for putting my mind at rest on that one, Alan) there still doesn't seem to be any solution. With our season of gite rentals starting in nine days, we are fretting a bit. Obviously some common sense on the guests' part would help the situation a bit, i.e. "don't swim at 2pm when it's 35 degrees, you're asking for a lot more trouble than wasp stings." But if last year is anything to go by, they'll swim even if the pool fencing has started to melt. By the way, if anyone else has this same problem like Alan and myself, don't waste your money on perfumed essential oils which supposedly repel wasps. Two bottles later and 40 Euros lighter, and no change - absolute garbage. Any more ideas folks? It can't just be me and Alan with wasps.........