The midges that plague the Scottish Highlands in summer may choose which people to bite because of their breath or sweat, say researchers at Aberdeen University.
In this month's Biologist , Jenny and Bill Mordue explain that signalling chemicals found in breath and sweat can act as attractants or repellents to midges.
They say: "Individuals who differ in their attractiveness to biting flies have different odour profiles." This may explain why some people escape midges while others seem to attract them.
These "tiny, abundant insects" cause considerable irritation. But they are difficult to control - controlling adult midges with pesticides would be "untenable", say the researchers.
Instead, the team has been investigating how signalling molecules, known as semiochemicals, could be used to lure the insects away from us.
In future, midge control programmes could be focused on the development of "push-pull" technologies.
Semiochemical-based repellents could be used to deter midges from biting potential hosts, while traps baited with specific attractants could be used to lure them away from certain areas.