the answer files

Why is the sky blue?

What is lightning?

What are the states of matter?

Does hot water freeze faster than cold?

Why does a can of Coke sink while a can of Diet Coke floats?

Why do you close your eyes when you sneeze?

Why do mosquitoes bite me more than my friends?

Why do your feet stink?

How does gravity work?

How fast does the space shuttle move in orbit?

What is escape velocity?

What would happen if you turned on your headlights while moving at the speed of light?

Why do mosquitoes bite me more than my friends?
Feeling persecuted? Are you the pick of the litter, as far as mosquitoes are concerned? Perhaps you're not being paranoid: experts tell us that some people attract five or ten times as many mosquitoes as others.

this won't hurt a bitBlack Salt Marsh mosquito and victim. ©University of Florida, Institute of Food and Agricultural Sciences.

The explanation may lie in the many ways mosquitoes can sense their prey (that's you, dear reader!). Mosquitoes can detect the carbon dioxide we exhale, the infra-red radiation from our bodies, and lactic acid and many other chemicals on our skin.

Since everybody exhales carbon dioxide, the unfair "prey selection" may lie with those other "come-hither" chemical signals. Ulrich Bernier, a research chemist with the U.S. Department of Agriculture's Agricultural Research Laboratory in Gainesville, Fla., has found about 350 chemicals on human skin. The chemicals are produced by us, by bacteria on the skin, or are just dregs of stuff we've recently touched.

The bad news is that more than 10 percent of the 125 chemicals he's tested so far are at least mildly attractive to Aedes aegypti, the vector for yellow fever and dengue fever.

The situation regarding attraction is confusing, Bernier says, since mosquitoes respond to several stimuli at once, and each species of skeeter may have particular preferences. Eventually, knowledge of attractive chemicals might enable the design of repellents that stymie those signals.

But his interim goal is to make superior skeeter attractants for traps. We can fantasize about a trap that would lure bloodsuckers away from the succulent primate meat lurking around a barbecue grill, but we can't buy such a trap yet. Bernier says he doesn't know of any trap in the world that is more toothsome -- from a skeeter's point of view -- than a human behind.

The Why Files took a big bite out of the mosquito menace.

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The Why Files
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