These robots are the result of years and years of work in swarm robotics. It's not enough to build a little drone that can do bees' characteristic waggle dance; the researchers needed to create a team of tiny bots that have a hive-mind of their own. They also needed to be able to move, act, and learn as a unit rather than a jumbled mess of machinery. For example, engineers from the University of Graz used artificial intelligence to evolve the robots' behavior to be more like that of real-life bees as the drones themselves became more sophisticated. They also got two robotic swarms to interact with each other, flying around as cohesive units without individuals flying off on their own, or crashing into one another.