As many of us discover at this time of year, when it comes to humans, mosquitoes have preferences. Their behaviour is fairly sophisticated, even if they do have tiny brains.
However it’s only the female mosquito that seeks us out, needing the proteins in our blood to produce their eggs. One of the most powerful clues they follow is carbon dioxide. Elevated carbon dioxide is a good signal for tracking people down, which is why it’s used by port officials searching lorries for people smuggling, and also in disaster relief for finding people buried in rubble. This is how mosquitoes find us, even if we’re wrapped in a sheet or through clothing.
Insect smell detectors, known as olfactory receptors, are highly developed allowing the mosquito to indulge very particular tastes: blood type and the range of bacteria on the skin provide the perfect bouquet. They can even distinguish between different types of perspiration. Much of what makes us particularly desirable is inherited, although alcohol does seem to attract them. There may be some truth to the old saying that in the night you’re too drunk to notice them and in the morning they’re too drunk to notice you.
Dr Daniel Glaser is director of Science Gallery at King’s College London
