In lowland wet forest habitats this is one of the most common Eciton species. Raids are always in columns, never in a carpet like E. burchellii. Raids can be day or night, and I frequently observe raiding columns ascending trees. Prey are often brood of vespid wasps and the ant genera Dolichoderus and Camponotus, suggesting that E. hamatum is mainly an arboreal forager.
Mexico to central Brazil, Bolivia. Type locality French Guiana. Costa Rica: wet forest lowlands throughout the country; absent in dry forest and montane areas.
Taxonomic history
Mayr, 1886b PDF: 121 (w.); Emery, 1896g PDF: 39 (m.); Wheeler, 1925d PDF: 145 (q.); Wheeler, 1943 PDF: 327 (l.).Combination in Myrmecia: Fabricius, 1804 PDF: 425.Combination in Atta: Latreille, 1809 PDF: 129; Leach, 1815: 147.Combination in Eciton: Latreille, 1804: 179; Latreille, 1817c: 75; Smith, 1855c PDF: 161.Combination in Eciton (Eciton): Emery, 1910b PDF: 20; Santschi, 1925b PDF: 12.Status as species: Fabricius, 1787 PDF: 311; Gmelin, 1790 PDF: 2803; Olivier, 1792: 502; Fabricius, 1793 PDF: 364; Latreille, 1802a PDF: 242; Fabricius, 1804 PDF: 425; Latreille, 1804: 179; Leach, 1815: 147; Latreille, 1817c: 75; Lamarck, 1817 PDF: 97; Smith, 1855c PDF: 161; Smith, 1858a PDF: 148; Mayr, 1863a PDF: 409; Roger, 1863b PDF: 36; Norton, 1868a PDF: 61; Norton, 1868b PDF: 45; Mayr, 1886b PDF: 117 (in key); Forel, 1886a PDF: 217; Emery, 1890c PDF: 38; Dalla Torre, 1893 PDF: 3; Emery, 1894d PDF: 176; Emery, 1894l PDF: 45; Forel, 1895b PDF: 119; Emery, 1896g PDF: 39; Forel, 1899b PDF: 22; Emery, 1900e: 176 (in key); Wheeler, 1907b PDF: 271; Forel, 1907h PDF: 2; Emery, 1910b PDF: 20; Forel, 1912d PDF: 41; Mann, 1916 PDF: 419; Crawley, 1916b PDF: 368; Forel, 1921b PDF: 133; Santschi, 1921g PDF: 88; Wheeler, 1921d PDF: 309; Mann, 1922 PDF: 19; Borgmeier, 1923: 38; Wheeler, 1923a PDF: 1; Wheeler, 1925a: 1; Santschi, 1925b PDF: 12; Borgmeier, 1936b PDF: 51; Santschi, 1939f PDF: 161; Borgmeier, 1953 PDF: 9; Borgmeier, 1955 PDF: 214 (redescription); Tafuri, 1957 PDF: 21; Borgmeier, 1958a PDF: 204; Kempf, 1960e: 387; Wheeler & Wheeler, 1964c PDF: 134; Kempf, 1970c PDF: 323; Kempf, 1972b PDF: 102; Watkins, 1976 PDF: 10 (in key); Watkins, 1982 PDF: 209 (in key); Wheeler & Wheeler, 1984a PDF: 269; Bolton, 1995b: 185; Palacio, 1999: 152 (in key); Branstetter & Sáenz, 2012 PDF: 254; Bezděčková et al., 2015 PDF: 109; Palacio, 2019 PDF: 601.Senior synonym of Eciton amazona: Borgmeier, 1953 PDF: 14; Borgmeier, 1955 PDF: 214; Kempf, 1972b PDF: 102; Bolton, 1995b: 185.Senior synonym of Eciton curvidentata: Shuckard, 1840e PDF: 174; Smith, 1858a PDF: 148; Mayr, 1863a PDF: 409; Roger, 1863b PDF: 36; Dalla Torre, 1893 PDF: 3; Forel, 1899b PDF: 23; Emery, 1910b PDF: 20; Borgmeier, 1923: 38; Borgmeier, 1955 PDF: 214; Kempf, 1972b PDF: 102; Bolton, 1995b: 185.Senior synonym of Eciton hamatum funesta: Borgmeier, 1953 PDF: 13; Borgmeier, 1955 PDF: 214; Kempf, 1972b PDF: 102; Bolton, 1995b: 185.Senior synonym of Eciton mattogrossensis: Borgmeier, 1953 PDF: 10; Borgmeier, 1955 PDF: 214; Kempf, 1972b PDF: 102; Bolton, 1995b: 185.Senior synonym of Eciton pittieri: Borgmeier, 1953 PDF: 9; Borgmeier, 1955 PDF: 214; Kempf, 1972b PDF: 102; Bolton, 1995b: 185.Senior synonym of Eciton testacea: Mayr, 1863a PDF: 409; Kempf, 1972b PDF: 102; Bolton, 1995b: 185.Eciton hamatum are one of the most studied species of army ants along with Eciton burchellii. E. hamatum are found from Mexico to Brazil and into northern Argentina (Gotwald 1995). Although E. hamatum act as predators within their ecosystem, they are beneficial in regards to maintaining species diversity, nutrient cycling, and because of their role as biological controls. E. hamatum will eat social insects such as bees and wasps (Bartholomew et al. 1987), but they are a specialized predator that preys upon other ants mainly (Powell 2011). During foraging, E. hamatum move among the surface in column raids to catch their prey and to emigrate as well. Within a colony, there are separate castes including the workers, the males, and the queen. Within the castes there are subcastes of workers that hold different tasks within the colony. Each colony nests inside of a bivouac, or a nest that is made out of the bodies of ants that are interlocked by their appendages (Gotwald 1995). Myrmecophiles are able to live within or are able to follow the borders of the bivouac and raiding columns to obtain leftover food or secretions from the hosts. Myrmecophiles are also known to live on the army ants themselves. Some myrmecophiles of army ants include snakes, phoretic mites, and various arthropods such as millipedes. These myremcophiles are able to steal prey, eat leftovers that the army ants leave behind, and can even devour the host (Gotwald 1995).
For mating to occur, a male from a foreign colony attempts to join the foraging column of another colony to mate with the queen. The ants from a foraging column are said to have sexual selection for foreign male ants that are closer is size and shape to the queen, but there is uncertainty behind this theory (Gotwald 1995). Once a foreign male has entered, copulation begins with the queen for approximately 10 hours. During this time, the male mounts the queen using his mandibles to hold onto the queen’s antennae, inserts his gaster into her abdomen, releases his sperm forcefully and proceeds to die (Gotwald 1995). At the time of reproduction, Eciton species are known to lay thousands of eggs per brood (Gotwald 1995). During the nomadic phase, the larvae and pupae have time to develop, and the phase only ends when the larvae pupate. The statary phase is the time in which the queen delivers new eggs. The eggs are given time to hatch and develop in the larval stage in the statary phase as well (Gotwald 1995).
E. hamatum are a polymorphic species that exhibits castes and subcastes. The castes include workers, soldiers, males, and queens. However, workers are divided into subcastes that can be simplified into small, medium, and large workers that have various functions within the army ant colony such as capturing prey or caring for the larvae (Gotwald 1995). Soldiers are specialized to defend the colony and gather prey while the males do not contribute to the colony other than by reproducing with the queen (Gotwald 1995). There is only one queen within a colony unless division occurs. During division, also called colony fission, new daughter colonies will form by half of the colony following the parent queen and half following the new daughter queen (Gotwald 1995).
While some species of ants are blind, it is believed that E. hamatum, with the exception of the queen, have reduced compound eyes to adapt to the dangers of foraging on the surface. The workers, soldiers, males, and queens all of distinct morphologies that distinguish one from another. For example, the workers have head widths that are less than or equal to 2.5 mm and a body mass of 1.8-19.4 mg (Feener 1988). The workers are also wingless and have small mandibles. However, soldiers have a head width that is greater than 2.5 mm with a body mass ranging from 16.0 mg to 27.4 mg. There is not a general trend on the leg length of army ants, but the workers lower their energy expenditure by carrying their loads in a specific manner. The ability of workers to carry loads under their bodies by lifting with their mandibles and placing the load in between their legs lowers energy costs unless they are carrying a load that exceeds their body mass (Bartholomew et al. 1987). The mandibles of soldiers are sharply pointed and large in comparison to the mandibles of workers (Feener 1988). The queen of the colony is wingless, with strong legs for emigration, and enhanced reproductive features such as an expanded abdomen. The morphology of the queens allows them to produce a high amount of eggs in a short amount of time (Gotwald (1995). To complement the queens, the males have specialized genitalia and mandibles for reproductive purposes. Whereas worker ants have mandibles that are used for predation, the mandibles of males are used to grasp onto the abdomen of the queens for reproduction (Gotwald 1995). Males are also winged, but they shed their wings or have them torn off by workers when they are allowed entry into a new colony (Gotwald 1995).
E. hamatumrelease pheromones for recruitment to do tasks such as defending the colony, constructing the bivouac, retrieving food, and emigrating (Gotwald 1995). In some instances, the raiding columns of E. hamatum will move for 200 meters or more from the bivouac during foraging (Bartholomew et al. 1987). For Eciton species, there are two phases of behavior or cycles to which they generally follow: the nomadic phase and the statary phase. The nomadic phase lasts from 16-18 days while the statary phase has a 18-21 day duration. During the nomadic phase, the bivouac moves daily to a new nesting site, sometimes greater than 100 meters (Bartholomew et al. 1987, Gotwald 1995). It has been found that foraging occurs 97%-100% of the time during the nomadic phase to feed the developing larvae (Teles Da Silva 1979, Gotwald 1995). The nomadic phase ends when the larvae pupate which then begins the statary phase. During the statary phase, foraging decreases immensely and more focus is placed on the queen laying a new brood of eggs and for allowing the pupae to mature (Bartholomew et al. 1987). The bivouac remains in one place during the statary phase, but colonies send out raiding columns to maintain the least amount of foraging necessary to feed the larvae hatched from the new brood (Bartholomew et al. 1987). The next nomadic phase begins when the pupae from the previous phase have emerged from their cocoons as young workers.
The morphology of E. hamatum has provided the ants with a direct way to defend themselves from predators by attacking them by biting or stinging, but these ants have also developed alarm signals. In response to crushed heads, E. hamatum will use an alarm signal to help evade and escape from predators (Lalor & Hughes 2011). The alarm signal, the release of 4-methyl-heptanone from their mandibular glands, can act as a panic response and can be signaled in an aggressive manner as well (Lalor & Hughes 2011). Therefore, E. hamatum are capable of using alarm signals as a means of escape and as a way of recruitment to begin attacking.
E. hamatum raid in columns normally in soil, leaf littler, and low vegetation diurnally (Gotwald 1995). Column raiding consists of small groups of workers from the colony that will forage in narrow columns that are connected to the bivouac (Teles Da Silva 1979). On average, each column raid will bring in approximately 15,000 to 40,000 prey every day. Each colony consists of approximately 150,000 adults and 60,000 larvae, with an estimated prey intake of 1 and 32 grams of dry weight per day. (Gotwald 1995, Powell 2011). Foraging workers that capture prey immobilize, dismember, and sectioned into pieces. The foraging workers are able to bite and sting while capturing their prey (Gotwald 1995).
Less foraging occurs during the statary phase, when the queen is laying eggs, than during the nomadic phase, when the colony emigrates. Considering they are diurnal foragers, E. hamatum have a period around 11:00 AM and 2:00 PM in which the amount of workers per every 1 to 2 meters decreases to approximately 1 worker. The reduced amount of workers during the day can be due to some of the risks associated with diurnal foraging such as temperature change (Gotwald 1995).
Despite the fact that Eciton species have developed many defenses against predators, both invertebrates and vertebrates prey upon them. Out of the invertebrates, other ants pose one of the biggest threats against army ants. Many vertebrates such as amphibians, insectivorous birds, anteaters, and other mammals have been known to prey upon army ants as well (Gotwald 1995).
[[ male ]] Opaco, ferrugineo chiaro, il dorso dell'addome, le suture del torace, una riga mediana sul mesonoto, Io scutello, ii vertice e le zampe piu scuri, le mandibole e le antenne brune. Addome e zampe pubescenti; tutto il corpo irto di peli fulvi piuttosto corti. Il tegumento e coperto di fittissima punteggiatura fondamentale, e sparso di numerose fossette dalle quali sorgono i peli ritti; solo i margini dei segmenti addominali sono lucidi e glabri nelle loro parti laterali. Il capo e largo quanto il torace. Le mandibole, vedute d'innanzi e semichiuse, appariscono angolose an margine esterno vicino alla base, poi quasi rette fino all'apice che e debolmente curvato e acuto, preceduto sul margine interno da un grosso dente; vedute di fianco si allargano dalla base fino oltre il terzo, dove ii margine posteriore (interno) offre un angolo ottuso, quindi procedono allargandosi insensibilmente un poco, per formare, prima dell'estremita, un angolo o grosso dente e restringersi bruscamente, con margine concavo, fino alia punta. Il torace e relativamente stretto; dietro lo scutello, discende quasi perpendicularmente, fino all'inserzione del peduncolo; il metanoto ha due sporgenze arrotondate. Il peduncolo e trapezoideo, con gli angoli rotondati, meno allargato indietro che nelle specie affini, distintamente depresso nel mezzo. Le ali sono giallo d'ambra, con la venatura ferruginea. L. 14 mm.
Di un altro [[ male ]] di Eciton , egualmente inedito ed affine ai precedenti, ebbi 3 esemplari del Paraguay dal Balzan. Appartiene verosimilmente all' E. vagans Ol. o all'i E. Rogeri Torre { mexicanum Rog .). Nel dubbio, lo descrivo con nome nuovo.
Eciton hamatum is a species of army ant in the subfamily Dorylinae; it is found from Mexico to central Brazil and Bolivia. The species differs from Eciton burchellii, in that it does not fan out into the underbrush when foraging. Rather, it forages in columns, often in trees and preying exclusively on the larvae of other social insects. Its prey are often broods of vespid wasps and ants of genera Dolichoderus and Camponotus, suggesting that E. hamatum is mainly an arboreal forager.[1]
They are known to make living bridges with their bodies over small gaps.[2][3]
Eciton hamatum is a species of army ant in the subfamily Dorylinae; it is found from Mexico to central Brazil and Bolivia. The species differs from Eciton burchellii, in that it does not fan out into the underbrush when foraging. Rather, it forages in columns, often in trees and preying exclusively on the larvae of other social insects. Its prey are often broods of vespid wasps and ants of genera Dolichoderus and Camponotus, suggesting that E. hamatum is mainly an arboreal forager.
They are known to make living bridges with their bodies over small gaps.
