Anybody see the new BBC1 Holiday prog last night? In one bit, they tested the theory that Vitamin B, Marmite, Yeast or the like keep mossies away. A brave doctor ate all of those, and Angela Rippon covered her hands and arms with a DEET repellent, then both stuck there hands in a box of hungry mossies. Angela no bites, the doctor over 20.
So stick with the chemicals folks- marmite didn't work!