Other swarm robotics research has looked at alternative resources such as alcohol, light and sound to simulate pheromones and swarm behaviour. However, these are complex and expensive methods compared to COS-phi, which simply combines the LCD screen and USB camera with an open-hardware micro-robot and an open source localisation system.
Oh, yeah, sure, those are other methods are really complex. All this this needs is to constrain the robots to roaming around on top of an LCD screen. That's practical.
Just because nature does something one way, doesn't mean it's the best way.