But as the Los Angeles Times reports, "a pocket-size drone dubbed the Nano Hummingbird for the way it flaps its tiny robotic wings has been developed for the Pentagon by a Monrovia [Calif.] company."
The company, AeroVironment Inc., says it "has accomplished a technical milestone never before achieved — controlled precision hovering and fast-forward flight of a two-wing, flapping wing aircraft that carries its own energy source, and uses only the flapping wings for propulsion and control." It can go up, down, forwards, backwards, sideways and flip over.
According to the Times, the little flyer has "a wingspan of 6.5 inches, the mini-drone weighs 19 grams, or less than a AA battery." The Pentagon has spent about $4 million so far on its development, with an eye on its potential for spy missions.