African Anopheles mosquitoes find us by our carbon-dioxide-rich exhalation. But when they get close they turn away from our heads and ___1___—apparently their preferred snack spot.

Biologist Remco Suer believes he’s figured out the mosquito behavior, for his doctoral thesis at Wageningen University in the Netherlands. And the answer might help in the fight against malaria.

Previous research identified odors produced by 10 bacteria that live on human feet and that, in combination, are attractive to mosquitoes ___2___. Suer's work shows that nine out of 10 of these odors are ___3___ by olfactory neurons under hair-like structures on the mosquitoes' mouthparts. Right nearby are some other key neurons—that recognize our CO2 from further away.

Suer discovered that five different bacteria scents, when isolated from the mix, actually ___4___ those CO2 neurons from doing their job. So if the bacterial odor molecule is present, the CO2 sniffers turn off, presumably to allow the mosquito to concentrate on the close-range foot target.

Suer imagines ___5___ baited with these feet bacteria to attract mosquitoes and catch them before they can bite. It’s the next best thing to stepping on them.
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