Mosquitoes can smell your ankles

She knows where you're exposed!

Credit: JJ Harrison, via Wikimedia

The deadliest animals in the world, female mosquitos, target their prey—us—because they are attracted to the carbon dioxide that we exhale. But just finding breathing human beings isn't really enough to guarantee the one big sip of blood the mosquito needs to get the nutrients necessary for laying eggs. Most mosquitoes can't bite through heavy clothing, so they need to head for exposed skin like ankles and ears. Finding that perfect spot to suck our blood depends on more than just carbon dioxide. If fact, experiments have shown that if you turn off the mosquito's ability to sense carbon dioxide, they can still detect and target human odors.

A team of scientists from the University of California Riverside studied mosquito sensory perception and wanted to figure out how the mosquitos sense our skin: which of our many body odor compounds do they recognize and what organs sense those compounds? They found that the same olfactory neurons on the mosquito' maxillary palp—the little sensory appendages around the mouth—that sense carbon dioxide also play a major role in identifying human body odors.

To test this, they needed some human body odors. They collected a bit of distinctive fragrance by having a couple of subjects rub their feet on some glass beads. They then watched as the test mosquito, Aedes aegypti, homed in on the beads even when placed in a small wind tunnel.