Mosquitoes  ruin countless American picnics every year, but around the world, this bloodsucking beast isn't just annoying--it causes a health problem. More than a million people die from the spread of mosquito-borne diseases like malaria and yellow fever each year. Attempts to control populations via insecticides like DDT have had ruinous side effects for nature and human health. Neurobiologist Leslie B. Vosshall has a different solution for stopping the insects and the spread of disease. "I believe the key to controlling mosquito behavior is to understand better how they sense us," she says. At their Rockefeller University lab, Vosshall and her colleagues are studying the chemical sensory processes by which mosquitoes choose hosts. How do they sense heat, humidity, carbon dioxide, and body odor ? What makes some people more attractive to a mosquito than others? It takes blood and sweat to find out. To study how mosquitoes assess body odor, Vosshall and her teammates might wear stockings on their arms and keep from showering for 24 hours to create sample smells, _ They insert their arms into the insects' hidden home to study how mosquitoes land, bite, and feed and then they document how this changes. This can mean getting anywhere from one bite to 400, depending on the experiment. Studying male mosquitoes is more pleasant. Since they don't feed on blood, the lab tests their sense of smell using honey. Vosshall and her team have also begun to study how genetics contribute to mosquitoes' choice of a host. She's even created a breed that is unable to sense carbon dioxide, an important trigger for the insects. "By using genetics to make mutant  mosquitoes, we can document exactly how and why mosquitoes hunt humans," Vosshall says. Once Vosshall figures out what makes mosquitoes flock to us, she can get to work on making them leave us alone. Many of her lab's proposed solutions sound simple enough, including bracelets  that carry long-lasting repellants  or traps that can reduce populations, but the breakthroughs, when they come, may save millions of lives in the developing world--and a lot of itching everywhere else. Why is it less challenging to study male mosquitoes?
They are not bloodsuckers. They are afraid of stockings. They have a poor sense of smell. They are protective of their hosts.