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In late December 2003, the CIA revealed many never-before-seen tools of the spy trade at its own museum near Washington. These included a listening device designed to look like tiger excrement that recorded troop movements in Vietnam, and a robot fish that collected water samples near hidden nuclear plants. Then, there was a tiny dragonfly.

At first glance, this 1970s Cold War artifact looked like any Common Green Darner (Anax junius) or maybe a Blue-faced specimen (Coryphaeschna adnexa) if you’re squinting—its face, forewings, and thorax were all in the right place. But look closer, and you see that this small bug isn’t really a bug at all. It's an “insectothopter,” a bug-sized spy that represents our first big step into the complex world of insect robotics. It was an incredible achievement at a time when the microprocessor was a novel invention.

Now, some 16 years after this public debut—and nearly 50 years since its first flight—newly released documents show every small detail about how the CIA created such an impressive micro-robot.

Putting the Bug In “Bugging”

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Schematics for the insectothopter, declassified and provided by The Black Vault.
CIA / The Black Vault

Despite being a star attraction at the CIA’s museum, many details about the bug remained a secret for decades until John Greenwald, founder of the anti-secrecy website The Black Vault, put in a request for documents under the Freedom of Information Act (FOIA) in the summer of 2013.

“I've learned over the years, the U.S. military and government often will acknowledge something or confirm something exists, and many times that largely satisfies the public's curiosity,” Greenwald told Popular Mechanics. “However...we often don't get the full story. So I go after documents never-before-released to tell either more of the story, or the real story.”

Seven years later in January 2020, Greenwald received a stack of documents detailing the dragonfly’s design and construction—and the story stretches back into spying’s peak during the Cold War.

"The old fellow plucked the insect from its perch and tossed it into the made about two circuits and landed nicely on the desk."

Back then, bugging—or listening in on conversations with electronic devices—was a powerful and relatively new espionage tool, but some places remained harder to reach than others.

So the agency turned to retroreflectors, tiny glass beads that reflect laser light (in this case, a laser beam) back at its source. This reflected laser beam can be affected by any vibration in the glass, which alters the distance that the beam travels. The CIA can then analyze the returned beam and recreate the vibrations that disturbed it, essentially extracting sound from light. In practice, these retroreflectors acted as a remote microphone to eavesdrop on any conversation. In 1970 the CIA already used a similar technology to pick up vibrations from window glass.

The real challenge was getting the small retroreflectors onto a window sill, over an embassy wall, or next to the right park bench at just the right moment while also remaining inconspicuous. The CIA had previously tried fitting a cat with a microphone, but the project ended in disaster. The agency needed another approach.

That’s when Don Resier, deputy head of the CIA’s Office of Research and Development, came up with an alternative. Instead of attaching microphones on common mammals, a robot insect could pass unnoticed. Dubbed the “insectothopter,” he assigned Charles Adkins to lead the project.

Adkins' goal was to build a device that could fly 200 meters and deliver 0.2 grams of retroreflector beads without being noticed. Resier thought a bee would be a good candidate, but the insect's complex flight mechanics wouldn’t be fully understood until decades later in 1999.

What Adkins really needed was stability because computers of the day were far too big and slow to handle complex controls. Luckily, one of Adkins’s fellow CIA scientists was a dragonfly enthusiast and had a preserved collection.

Common Green Darner
Common green darner
Encyclopaedia BritannicaGetty Images

According to Adkins, this scientist, whose name remained redacted in the FOIA documents, said that a dragonfly’s aerodynamics were much more stable. In addition to being incredibly maneuverable, dragonflies are exceptionally good gliders compared to other insects, which helps them conserve energy on long flights. The scientist brought in some specimens, and when Adkins pressed him on the issue, “the old fellow plucked the insect from its perch and tossed it into the air,” Adkins wrote. “It made about two circuits and landed nicely on the desk.”

The demonstration convinced Adkins, but the team still needed to figure out how to replicate a dragonfly’s wings, which flap 1,800 times per minute. To pull this off, scientists used a tiny fluidic oscillator, a device with no moving parts that’s completely driven by gas produced by lithium nitrate crystals. When initial tests showed that the prototype couldn’t carry the required 0.2 gm payload, designers added additional thrust by venting exhaust backward, much like jet propulsion.

After a quick dragonfly-inspired paint job, the drone was ready for (covert) action, weighing just under a gram. Its glittering ‘eyes’ were the glass retroreflector beads destined to snoop on unsuspecting targets.

The Crosswinds of Reality

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While the CIA now had its robo-bug, it still needed a way to control it.

Radio control was out of the question because any extra weight would doom the small insectothopter. So CIA scientists turned to the same lasers used for the retroreflectors. This was a portable laser unit, known as ROME, that produced an invisible infrared beam. The idea was that the laser would heat a bimetallic strip that would then open or close the dragonfly’s exhaust. While effectively throttling the ‘engine,’ another laser—acting like a kind of rudder—would then steer the drone to its desired destination.

With its gas-pumping engine and laser-based navigation system, the insectothopter could fly for only 60 seconds. But this was more than enough to get the dragonfly—and its payload—to a target some 200 meters away. Seeing as there was no landing gear, the dragonfly was likely a crash and perch operation.

“The feasibility of a controlled insectothopter vehicle with limited operational capability has been investigated and all program goals to this point have been achieved,” Adkins said in his final 1974 report.

The first flight of the insectothopter, according to the CIA.

While the dragonfly proved to be an incredible feat of engineering—and worked perfectly under testing conditions—a laboratory rarely resembles reality. The biggest problem with the insectothopter's design was that an operator had to keep a laser manually trained on the drone during flight. Easily done in a static wind tunnel, less so in blustery and unpredictable conditions.

“Flying in a straight line in still air is not that difficult. It’s a bit like a paper airplane, especially if you give it a boost with some compressed gas,” Simon Walker, an expert in biomechanics at the University of Leeds in the U.K., told Popular Mechanics. "If you examine the veins in a dragonfly’s wing, it forms part of an incredibly complex, deformable structure that bends in particular ways under stress, and that deformability is really important to the aerodynamics.”

In theory, the insectothopter could still be flown in less than 7 mph winds, but “the ultimate demonstration of controlled powered flight has not yet been achieved,” Adkins ultimately reported. “Though the flight tests were impressive, control in any kind of crosswind was too difficult.”

The program cost $140,000, about $2 million today, which is pocket change when you consider the billions spent on modern spy satellites. But no CIA missions ever required the agency’s new dragonfly spy, and the project shut down.

Dragonfly Descendants

The Delfly micro-drone captured with a slow-motion camera at 6,000 frames per second.

In the past 50 years, our understanding of insect flight—and the electronics needed to replicate it—have advanced tremendously, even if nature still has a leading edge.

"We still can’t build something as effective as a bumblebee wing which still works well even when it is damaged,” Walker says, but he points to the Skeeter drone, developed by Animal Dynamics, as a good example of how our greater understanding of biomechanics can create a true heir to the insectothopter.

An agile micro-drone, Skeeter is also inspired by dragonflies with its four flapping wings. While the insectothopter could not handle a mild breeze, the Skeeter can manage “high gust wind conditions with greater tolerance and endurance than existing quadcopter equivalents,” according to the company.

Researchers at the University of Delft have also been working on a variety of robot dragonflies since 2005. Their smallest, the Delfly Micro, weighs just three grams and has a four-inch wingspan. This robo-bug can fly for three minutes on battery power and is far more agile than its ancestor. It can also relay images from a video camera, something the CIA’s designers could only dream of.

Other projects are even more exotic than the CIA’s original ideas. In 2017 researchers at Charles Stark Draper Laboratory created a cyborg dragonfly. Scientists modified a living dragonfly so it could be steered by remote control using "steering neurons" implanted in its eyes.

While all these concepts far surpass the CIA's initial efforts, they also receive the all-important benefit of a half-century of technological evolution.

“We hear about drones today over and over,” says Greenwald. “This was an unmanned drone from the 1970s, the size of a bug. The 1970s! Just think what type of advancements they can make in 50 years.”

While the original insectothopter never succeeded, Adkins and his team stumbled upon a stable platform for future insect robotics. What would a similar CIA drone look like in 2020? Who knows—that remains classified.

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