This tiny, flying robot flaps its wings 30 times per second—just like a real hummingbird—and will one day save lives by searching for survivors in wreckage and spots not easily accessible by humans.

A robot hummingbird is the military's latest flying spy machine, with a camera affixed to a featherweight 6.5-inch body that flies by flapping its wings. The "Nano Hummingbird" can fly just 11 miles ...