Engineers at the Massachusetts Institute of Technology have developed robotic lightning bugs that emit light when they fly. Think fireflies, but with what the robot's creators call electroluminescent soft artificial muscles for flying. Their tiny artificial muscles control the robot's wings and emit colored light during flight, which provides a low-cost way to track the robots and also could enable them to communicate. Their light, which offers a way for researchers to track the robots, could one day make the machines useful for search-and-rescue missions. In dangerous locations, the robots could signal for help by flashing their lights.