page_title: Leafcutter ant
section_title: Colony hierarchy
hierarchical_section_title: Leafcutter ant / The lifecycle of a leafcutter ant colony / Colony hierarchy
caption_attribution_description: English: Leaf cutter ants Atta cephalotes (Bug World, Bristol Zoo, England). The grey piece is a wire binding the rope.
context_page_description: Leafcutter ants, a non-generic name, are any of 47 species of leaf-chewing ants belonging to the two genera Atta and Acromyrmex.
  These species of tropical, fungus-growing ants are all endemic to South and Central America, Mexico, and parts of the southern United States. Leafcutter ants can carry twenty times their body weight and cut and process fresh vegetation to serve as the nutritional substrate for their fungal cultivates.
  Acromyrmex and Atta ants have much in common anatomically; however, the two can be identified by their external differences. Atta ants have three pairs of spines and a smooth exoskeleton on the upper surface of the thorax, while Acromyrmex ants have four pairs and a rough exoskeleton.
  Next to humans, leafcutter ants form the largest and most complex animal societies on Earth. In a few years, the central mound of their underground nests can grow to more than 30 m across, with smaller radiating mounds extending out to a radius of 80 m, taking up 30 to 600 m² and containing eight million individuals.
context_section_description: In a mature leafcutter colony, ants are divided into castes, based mostly on size, that perform different functions.  Acromyrmex and Atta exhibit a high degree of biological polymorphism, four castes being present in established colonies—minims, minors, mediae, and majors.  Majors are also known as soldiers or dinergates.  Atta ants are more polymorphic than Acromyrmex, meaning comparatively less difference occurs in size from the smallest to largest types of Acromyrmex.
  Minims are the smallest workers, and tend to the growing brood or care for the fungus gardens.  Head width is less than 1 mm.
  Minors are slightly larger than minima workers, and are present in large numbers in and around foraging columns. These ants are the first line of defense and continuously patrol the surrounding terrain and vigorously attack any enemies that threaten the foraging lines. Head width is around 1.8–2.2 mm.
  Mediae are the generalized foragers, which cut leaves and bring the leaf fragments back to the nest.
  Majors, the largest worker ants, act as soldiers, defending the nest from intruders, although recent evidence indicates majors participate in other activities, such as clearing the main foraging trails of large debris and carrying bulky items back to the nest. The largest soldiers (Atta laevigata) may have total body lengths up to 16 mm and head widths of 7 mm.
caption: Leafcutter ant Atta cephalotes
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