From [HERE] Is that buzz above your head an insect, or is it a miniature flying machine? 

With current technology and progress in mechanical miniaturization, anything could be possible. Even back in the Cold War days, the CIA had come incredibly close to building such a bug that looked and flew exactly like a dragonfly.

In the 1970s, the United States’ Central Intelligence Agency’s Office of Research and Development developed a miniaturized listening device that needed a system to which it can attach and be delivered to unsuspecting marks. The Agency’s scientists decided that the delivery system should be a miniature unmanned aerial vehicle that can hover near or above the target, covertly recording their conversation. 

At first they considered building a flying machine in the shape of a bumblebee. But bumblebees had erratic flying patterns, and if one was found stopping and hovering in mid air, it would have certainly roused suspicion. So, the bumblebee was discarded. Then an amateur entomologist on the project suggested a dragonfly. Dragonflies are nimble flyers. They are able to hover, glide, and even fly backward. They are native to every continent except Antarctica, so their presence would be unremarkable.

And thus, the Insectothopter was born. It was 6 centimeters long, and had a wingspan of 9 centimeters, which was well within the range of an actual dragonfly’s dimensions. The Insectothopter had a miniature engine to move the wings up and down at the proper rate to provide both lift and thrust. A small amount of gaseous propellent was used to drive the engine, and the excess was vented out the rear for extra thrust. A laser beam provided guidance and acted as the data link for the miniature acoustic sensor onboard the craft.

Initial flight tests were impressive. The Insectothopter could 200 meters in 60 seconds, but only when there was no wind. Weighing at just one gram, even the gentlest breeze blew the Insectothopter off course. 

Although a novel invention, the Insectothopter never flew an actual spy mission. [MORE]