SAN DIEGO // The Pentagon has poured millions of dollars into the development of tiny drones inspired by biology, including the hummingbird, each equipped with video and audio equipment that can record sights and sounds.
They could be used to spy, but also to locate people inside earthquake-crumpled buildings and detect hazardous chemical leaks.
Besides the hummingbird, engineers in the growing unmanned aircraft industry are working on drones that look like insects and the helicopter-like maple seed.
Researchers are even exploring ways to implant surveillance and other equipment into an insect as it is undergoing metamorphosis. They want to be able to control the creature.
The devices could end up being used by police officers and firefighters.
Their potential use outside of battle zones, however, is raising questions about privacy and the dangers of the winged creatures buzzing around in the same skies as aircraft.
For now, most of these devices are just inspiring awe.
The remote-controlled bird, with a 16.5cm wing span, weighs less than an AA battery and can fly at speeds of up to 17 kph, propelled only by the flapping of its two wings. A tiny video camera sits in its belly.
The bird can climb and descend vertically, fly sideways, forwards and backwards. It can rotate clockwise and anti-clockwise.
Most of all it can hover and perch on a window ledge while it gathers intelligence, unbeknown to the enemy.
Matt Keennon, a senior project engineer of California's AeroVironment, which built the hummingbird, said: "We were almost laughing out of being scared because we had signed up to do this."
The Pentagon asked them to develop a pocket-sized aircraft for surveillance and reconnaissance that mimicked biology. It could be anything, they said, from a dragonfly to a hummingbird.
Five years and US$4million (Dh14.68m) later, the company has developed what it calls the world's first hummingbird spy plane.
"It was very daunting up front and remained that way for quite some time into the project," he said, after the drone blew by his head and landed on his hand during a media demonstration.
The toughest challenges were building a tiny vehicle that could fly for a prolonged period and be controlled or control itself.
AeroVironment has a history of developing such aircraft, however. Over the decades, the company, based in Monrovia, California, has developed everything from a flying mechanical reptile to a hydrogen-powered plane capable of flying in the stratosphere and surveying an area larger than Afghanistan at one glance. It has become a leader in the hand-launched drone industry.
Lockheed Martin has developed a fake maple seed, or so-called whirly bird, loaded with navigation equipment and imaging sensors. The plane weighs less than 2grams.
On the far end of the research spectrum, the Defence Advanced Research Projects Agency is also exploring the possibility of implanting live insects during metamorphosis with video cameras or sensors and controlling them by applying electrical stimulation to their wings.
The idea is for the military to be able to send in a swarm of bugs loaded with spy gear.
The military is also eyeing other uses. The drones could be sent in to search buildings in urban combat zones. Police are interested in using them, among other things, to detect a hazardous chemical leak. Firemen could fly them over a disaster zone to get better data quickly.
It is hard to tell what, if anything, will make it out of the lab, but their emergence presents challenges and not just with physics.
Peter W Singer, the author of the book Wired for War, about robotic warfare, questioned the legal implications, especially with interest among police in using tiny drones for surveillance, and their potential to invade people's privacy.
Mr Singer said these questions would be increasingly discussed as robotics became a greater part of everyday life. "It's the equivalent to the advent of the printing press, the computer, gunpowder," he said. "It's that scale of change."