US intelligence agencies were just as obsessed with drone spying 40 years ago as they are nowadays - only then, it was pipe-smoking entomologists and watchmakers who were in charge of building prototypes. Back in the '70s, the CIA needed some kind of miniature flyer to deliver an audio bug, and after considering (and rejecting) a faux bumblebee, decided that a robotic dragonfly would be the best option. The wee UAV used a "miniature fluidic oscillator" as a motor and was propelled by a small amount of gas.
Engadget , CIA dragonfly drone almost beat modern UAVs by 40 years, was swatted (video), CIA dragonfly drone almost beat modern UAVs by 40 years, was swatted (video)