Meet the CIA’s insectothopter.

It was the 1970s, the Cold War was in full swing, and the U.S. Central Intelligence Agency’s Office of Research and Development had developed a miniaturized listening device. Engineers were wise to choose the dragonfly. Dragonflies are nimble aerialists, able to hover, glide, and even fly backward. They can turn 180 degrees in three wingbeats. The Insectothopter’s 6-⁠centimeter-long body and 9-cm wingspan were well within the range of an actual dragonfly’s dimensions. Plus, dragonflies are native to every continent except Antarctica, so their presence would be unremarkable, at least in the appropriate season.

https://spectrum.ieee.org