Army ant

Army ant (or legionary ant or "Marabunta") means over 200 ant species. They are called army ants due to their aggressive predatory groups looking for food, known as "raids", in which many ants look for food at the same time in one place, attacking other animals collectively.
Army ants do not build a nest like most other ants. Instead, they build a living, temporary nest with their bodies. All army ant species are part of the ant family, Formicidae. There are several kinds that have evolved on their own the same behavior. This is called "legionary behavior", and is convergent evolution.
Usage.
Before, "army ant" meant ants from 5 different ant subfamilies: in two of these subfamilies, the Ponerinae and Myrmicinae, it is only a few species that show legionary behavior; in the other three subfamilies, Ecitoninae, Dorylinae, and Leptanillinae, "all" of the species are legionary. Now, another subfamily Leptanilloidinae, is called army ants.
A 2003 study of thirty species (by Sean Brady of Cornell University) shows that the ecitonine and doryline army ants evolved from one group in the mid-Cretaceous period in Gondwana, and so the two subfamilies are now one called Ecitoninae, but not everyone says this.
These are army ants: