page_title: Eciton burchellii
section_title: Colony structure
hierarchical_section_title: Eciton burchellii / Colony structure
caption_attribution_description: English: Eciton burchellii army ants
context_page_description: Eciton burchellii is a species of New World army ant in the genus Eciton. This highly charismatic species performs expansive, organized swarm raids that give it the informal name, Eciton army ant. This species displays a high degree of worker polymorphism. Sterile workers are of four discrete size-castes: minors, medias, porters, and soldiers. Soldiers have much larger heads and specialized mandibles for defense. In lieu of underground excavated nests, colonies of E. burchellii form temporary living nests known as bivouacs, which are composed of hanging live worker bodies and which can be disassembled and relocated during colony emigrations. Eciton burchellii colonies cycle between stationary phases and nomadic phases when the colony emigrates nightly. These alternating phases of emigration frequency are governed by coinciding brood developmental stages. Group foraging efforts known as "raids" are maintained by the use of pheromones, can be 200 metres long, and employ up to 200,000 ants. Workers are also adept at making living structures out of their own bodies to improve efficiency of moving as a group across the forest floor while foraging or emigrating.
context_section_description: Colonies may be quite large, accommodating as many as 100,000 to 600,000 adult individuals. Each colony consists of a single queen, a brood of developing young, and many adult workers. The adult workers make up the majority of the population. There are four distinct physical worker castes. The queen usually copulates with 10–20 males, which leads to a colony with a large number of worker patrilines, which are full-sibling families with the same father and mother. When a colony's size reaches a maximum, it can result in a split in the colony, with the old queen heading one resultant swarm and a daughter heading the other.
caption: Size differences between the major workers and minors
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