A group of US Marines hunker down beside a building, enemy fire coming at them from somewhere up ahead. One soldier reaches into his pack and pulls out a few robots that look like large bugs. The bots fly down the street, sending back images that show where the enemy troops are hiding, how many there are and what weapons they're using.

That's not all. In the same data stream, the robots also send back an audio recording of what the snipers are saying, along with infrared pictures. Armed with the real-time surveillance information, the Marines can maneuver out from under the attack and get to safety.

This scenario is what engineers at BAE Systems picture as they begin developing the miniature robots for the US Army Research Laboratory. The robotics company recently signed a US$38 million deal to design and create the micro-robots inspired by birds and insects.

The robots, according to BAE CTO Aaron Penkacik, will work as a distributed system - or swarm - to gather information and send it back in one unified stream. For instance, a small group of robots, the size of large insects, might include one robot that captures video, another that records sound and another that senses chemical agents. The robots will share the information and send it back to the command center, or soldier, as one unified message.

Scientists at BAE just started designing the system in what is laid out to be a five-year project. Penkacik, though, said he hopes US soldiers might actually be using a basic model of the spy bots earlier, while engineers continue working to refine the machines.

"We're not just trying to make a little gadget," he said. "We're trying to make a system that performs a useful military surveillance and reconnaissance function. It's not about the individual robots. It's about the system."

Penkacik noted that spy bots are nothing new, especially in military operations. The new robots, though, will be set up to work as a swarm and they'll be smaller than many of the spy bots used now. He said he envisions that the BAE robots will be of varying sizes - some the size of birds, others the size of bugs.

"We're trying to make them difficult to detect," he added. "You might have a Marine in an urban combat situation and he might need to know what's going on around a corner two blocks away or in a building across the street. Some [robots] will be ground based. They'll crawl or walk. They might be deployed inside a building to map out hallways. Others will be airborne and they'll be conducting surveillance and planting sensors. If there's enemy action, they can survey it and send the data back. If that enemy activity moves down the street or to an adjacent building, it will go with them."

Because the engineers will be trying to get so much technology inside a tiny - and lightweight -- machine, Penkacik said they will have to be creative. Legs, for instance, could also be used as antennas. The wings could be solar cells to recharge the bot's power source.

The big challenge, though, will be in making the robots work collaboratively, thinking and moving much like a swarm of bees.

"We need to work on collaborative behavior with multiple robots so they can do distributed data fusion in an ad hoc network that's moving in real time," said Penkacik. "Think about a swarm of bees and the way they fly and stay in formation. We're looking to mimic some of that stuff. All the information you get from these different sensors is what we're looking at to create knowledge that helps the war fighter stay alive."

BAE will be working on the project with the University of California at Berkeley, the California Institute of Technology and the Jet Propulsion Laboratory, the Georgia Institute of Technology, the University of New Mexico, and North Carolina Agricultural and Technical State University.