This Is Why Some People Get So Many Mosquito Bites

Here you are, having fun at an outdoor party, when the 'uninvited guests' drop by. From long distances, mosquitoes track you by the CO2 plume you exhale, says Jorge Rey, PhD, director and professor at the Florida Medical Entomology Laboratory. Although everyone exhales about the same amount of CO2 individually, the total amount is exponentially higher the larger the group you're with. Translation: The crowd attracts them. From longer distances, mosquitoes are also attracted to movement and dark colors (which they can see better). When they close in, they then find you via your body chemistry. Your best defense—besides being antisocial or putting on lighter-colored clothing—is wearing repellent. DEET, picaridin, IR3535, oil of lemon eucalyptus and 2-undecanone are five effective ingredients to look for on labels, says the EPA. Long-sleeved shirts and pants will also help protect against bites.