Hello Paddy
I can only tell you of my personal experience...I am like a magnet to mosquitos! Last summer I travelled up and down the Turkish coast and adjacent Greek islands and was bitten consistentley, the worst being around Gocek. I spent a week at my house in Calis, and during that time (September), we had nightly BBQ's outside...and I was not bitten at all. Over the past few years we have noticed that there are less and less mosquitos and see the spraying van coming round frequently ( I think that they use diesel fumes to kill or drive mosquitos away - no doubt the good people of CBF will probably correct me). There is more and more development around the calis area and hence the sections of 'swamp' waste land is decreasing.
Best Wishes
Lorraine