A question about these Army Ants invading a wasp nest.

[El Lobo Gordo]

Ants can walk upside down on ceilings perfectly well so it is no mystery as to how they were able to invade the wasp nest and defeat their enemy. However, carrying away the spoils of war upside down on ceilings is not so easy for ants....cause you know...gravity. My question is: How did the ants decide to build a bridge that allows them carry away the spoils of war and how did they decide where to place it?



I thought about this and I think I know the answer but I am curious as to what others think the explaination could be.