(Video Link)
David Hu and Nathan J. Mlot of the Georgia Institute of Technology investigated claims that when flooded out, fire ants will link together to form effective rafts:
"They'll gather up all the eggs in the colony and will make their way up through the underground network of tunnels, and when the flood waters rise above the ground, they'll link up together in these massive rafts," Mlot said. Together with Georgia Tech systems-engineering professor Craig Tovey, the scientists collected fire ants and dunked clumps of them in water to see what would happen.
In less than two minutes the ants had linked "hands" to form a floating structure that kept all the insects safe. Even the ants down below can survive this way, thanks to tiny hairs on the ants' bodies that trap a thin layer of air.
"Even when they're on the bottom of the raft, they never technically become submerged," Mlot said.
As the above video shows, the rafts stay together even under substantial pressure.
Link via Geekosystem