An Ant Convention---More than Meets the Eye?

After years of observing nature, I've learned that there is sometimes more than meets the eye. Take this photo of ants on a leaf for example.

I observed the ants for quite some time. They moved around the leaf but acted as if there was some major importance attached here. The white specks of the leaf appeared to be just a natural result of fall descending. Yet the ants seem to be after something. Perhaps there's something here that I didn't see?