Mosquitoes have remarkably refined powers of smell. The insects that spread malaria across sub-­Sa­har­an Africa come exquisitely equipped to find human blood. They home in on the scent of human breath and sweat and swiftly insert their needlelike mouthparts into the target’s skin. As they dine, their saliva transmits the malaria parasite into the wound. With a simple bite, they can ultimately take a life.