The almost 3,000 species of mosquitoes in the family Culicidae (of the 150 found in North America, 63 call New Jersey home, which makes NJ the mosquito capital of the country) have been around for over 30 million years. During that time they've become highly specialized in seeking out and feeding on blood, from which females get the protein and iron required to develop eggs (males don't drink blood, and for sustenance, both sexes feed on nectar).
Mosquitoes have chemical sensors that can pick up carbon dioxide and lactic acid from up to 100 feet away. Once they've been tipped off that there's someone or something breathing nearby, they follow their noses to hone in on their prey, insert their proboscis and begin feeding. Their saliva contains a grab bag of proteins that affect blood vessel dilation, blood clotting and platelet aggregation, which makes grabbing a meal easier, but also leaves us with red itchy "bites" (though they don't actually bite us, it's more of a stab than anything) as our immune systems break down these proteins.
They Love You, They Really Love You
After a summer barbecue, does it seem like you're covered head to toe by these bites while people who were sitting right next to you only have one or two? It's not paranoia, because the "˜skeeters actually are out to get you.
Remember when I said that mosquitoes follow their nose to you? I wasn't just being cute. I meant that they actually use an odor-based navigation system to find suitable victims. Proteins in their antennae, heads and noses latch on to chemical compounds emitted from our skin, and some of us just happen to give off odors that they find simply irresistible.
And the person sitting next to you, laughing silently as you get eaten alive? They're not special, they just smell different. Their body emits chemical compounds that make them unattractive to mosquitoes either by acting as repellents or by masking the compounds that mosquitoes would find attractive (we're not sure which way it goes, yet, but those intrepid entomologists are looking into it).
Scientists at Rothamsted Research (an agricultural research center in the UK) are also working to figure out which odors attract mosquitoes and which ones repel them. Thus far, thirty chemical compounds that definitely turn mosquitoes off have been identified and may be the key to the next wave of bug sprays.
This question was asked, during a fit of scratching, by my girlfriend Erica. If you've got a burning question that you'd like to see answered here, shoot me an email at flossymatt (at) gmail.com. Twitter users can also make nice with me and ask me questions there. Be sure to give me your name and location (and a link, if you want) so I can give you a little shout out.