Once the workers deposit their leaves, the tiny nurser workers chew them up and lay them down. They also tend for the larvae and eggs in the colony. The gargantuan soldiers defend the colony and provide escort to the workers from enemy ants and predators. Hunter' spiders are spiders that do not trap their pray, but actually chase it. They also prey on ants.
Anteaters also eat ants, hence their name.
There is even an insect called the antlion that builds a trap nest similar to an ant's. The nest lures ants to its opening, where the antlion awaits it with gaping jaws. Ants may very well compete with members of their own species, regardless of color. In fact, it is more likely that these ants will attack their own species since they get food from a common source. This is why soldiers are essential parts of any colony.