The swarm raids of Eciton burchellii are the largest of any Neotropical army ant, with over 200,000 individuals proceeding at a rate of up to 20 metres per hour (6). The foraging workers spread out in a fan-shaped swarm with a broad front (6) and the ants maximise their foraging efficiency by forming ‘traffic lanes’, destroying all arthropods that occur in their path. The lanes are separated by different pheromone trails, which are laid down by the outgoing and incoming ants (7).
Army ant workers form super-efficient teams to carry large prey items (8) and will even plug holes with their bodies to increase the flow of ants across rough terrain (9). Using such ingenious methods, the ants are able transport more than 3,000 prey items per hour, in raiding columns that can exceed 100 metres in length (7). In the course of a day’s raiding, a single Eciton burchellii colony is able to capture around 30,000 prey items (4).
Eciton burchellii has a fixed 35-day activity cycle of raiding and migration that is associated with the growth of new broods of workers in the colony (10). For 20 days, the colony remains in a fixed bivouac at a single nest site, and will only raid every few days. During this time, which is known as the ‘statary phase’, the queen will produce up to 100,000 eggs (4) (6).
The eggs of Eciton burchellii develop in synchrony and hatch into larvae at the end of the 20-day statary period. The colony then moves into a ‘nomadic phase’ which lasts for 15 days. During this nomadic phase, when the colony has larvae to feed, the ants perform mass swarm raids every day and migrate to a new nest site each night (6). At the end of the 15 days the larvae pupate, and the colony once again enters the statary phase (4).