The last time I got stung was approx 10 000 km ago. I remember it quite well, it was the same day I got my new Polar heartrate monitor. I guess it really is the luck of the draw with these bees and wasps.
My wife has come up with a novel idea (this is the women who famously dressed my wounds with tupperwear so that I would not stick to the sheets....) - Line the vents in the helmet with the material used in screendoors - air could pass through, but not the evil bastards. I'll try this and show you the results later.