An earlier version of this story was originally broadcast July 1, 2012.
(CBS News) The Fourth of July is a day for parades and fireworks and picnics and outdoor activities of every kind. Just don't forget to bring the mosquito repellant. Mosquitoes are the unwelcome guests at many an outdoor party, and not just because they're annoying. Tracy Smith reports our Cover Story:
They're as much a part of summer as watermelon and sunburns. Mosquitoes are found in every state, on every continent (except Antarctica).
"I love mosquitoes," said Leslie Vosshall, who runs Rockefeller University's Laboratory of Neurogenetics and Behavior in New York City. Along with her staff, she is trying to find out exactly how mosquitoes hunt humans.
"I have completely fallen in love with mosquitoes," Vosshall said. "They're beautiful creatures. They have beautiful behaviors. But they're dangerous."
"Most people, if you said, 'Mosquitoes are beautiful,' would tell you you're crazy," said Smith.
"Exactly. I get that a lot," she laughed.
She's really not crazy - but her dedication to her work seems jaw-droppingly insane, especially around feeding time, when Vosshall sticks her arm into a mosquito cage: "These are hungry girls and some boys," she said. Vosshall needs healthy mosquitoes for her work, and this, she says, helps keep them that way.
Only female mosquitoes bite, and only then because they need the blood to make eggs.
There are several ways to feed lab mosquitoes: this way, Vosshall says, is the best, despite what it does to her arm. "I feel good," she said. "I've done my job."
The telltale welts are the body's reaction to the saliva mosquitoes inject to make your blood flow. Over time, her body has become accustomed to this routine. Still, there's nothing routine about her work.
"What's interesting is that the really dangerous disease-causing mosquitoes have acquired a taste for humans," she said. "So Anopheles gambiae, which spreads malaria, the principle vector of malaria, prefers humans over all other animals."
Besides anopheles, some other mosquitoes high on the human misery list are the dengue fever carrier Aedes aegypti, that, in this country, is found mostly in the Southeast; and Culex pipiens, a carrier of West Nile virus, that can be found coast to coast. They all have a taste for us . . . and some of us are mosquito magnets.
Researcher Lindsay Bellani turns mosquitoes loose on a volunteer's bare arms. "We measure how many are trying to bite the person after five minutes," Bellani explained.
Scientists have yet to pinpoint what drives mosquitoes wild, but there's evidence that people with higher levels of sugar in their blood can be more appetizing to a hungry mosquito who can typically smell dinner 50 yards away.
"They're not working off of very much, but they do it so, so well," said Bellani, "and in some way I've developed a weird kind of respect for mosquitoes."
The Centers for Disease Control and Prevention has respect for mosquitoes, too. The agency was created in 1946 to fight malaria, and while malaria's been all but wiped out in the U.S., there were nearly 6,000 reported cases of West Nile virus here last year.