Eciton
Encyclopedia
The New WorldNew World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
army ant
Army ant
The name army ant is applied to over 200 ant species, in different lineages, due to their aggressive predatory foraging groups, known as "raids", in which huge numbers of ants forage simultaneously over a certain area, attacking prey en masse.Another shared feature is that, unlike most ant...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Eciton contains the most familiar species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of army ants. The most predominant and well-known species is Eciton burchellii
Eciton burchellii
Eciton burchellii is the predominant species of the genus Eciton and a type of New World army ant. Distinct in its expansive, highly organized swarm raids, it is often considered the archetypal species of "army ant" — so much that the term has become its common name — and remains one of...
, whose common name is "army ant" and which is considered to be the archetypal species.
Eciton burchellii
Eciton burchellii
Eciton burchellii is the predominant species of the genus Eciton and a type of New World army ant. Distinct in its expansive, highly organized swarm raids, it is often considered the archetypal species of "army ant" — so much that the term has become its common name — and remains one of...
and Eciton hamatum
Eciton hamatum
Eciton hamatum is a species of army ant in the subfamily Ecitoninae, present from Mexico to central Brazil and Bolivia. This species differs from many others 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...
are the most visible and best studied of the New World army ants because they forage above ground and during the day, in enormous raiding swarms. Their range stretches from southern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
to the northern part of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
.
Life cycle
Eciton army ants have a bi-phasic lifestyle in which they alternate between a nomadic phase and a stationary stage. In the stationary or statary phase ("statary" means "standing in place"), which lasts about three weeks, the ants remain in the same location every night. They make a nest out of their own bodies, protecting the queen and her eggs in the middle. This temporary home is known as a "bivouacBivouac (ants)
A bivouac is a structure formed by migratory army ant and driver ant colonies, where a nest is constructed out of the living ant worker's own bodies to protect the queen and larvae, and is later deconstructed as the ants move on....
". In the nomadic phase the ants move their entire colony
Ant colony
An ant colony is an underground lair where ants live, eat and mate. Colonies consist of a series of underground chambers, connected to each other and the surface of the earth by small tunnels. There are rooms for nurseries, food storage, and mating...
to a new location nearly every night for two weeks.
When the ants enter the statary phase, the queen's body swells massively and she lays as many as 250,000 eggs in less than a week. While the eggs mature, the ants swarm with less frequency and intensity. When the eggs hatch, the excitement caused by the increased activity of the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e causes the colony to enter the nomadic phase. The colony swarms much more intensely and nearly every day, and the ants move to a new location every night. After two weeks, around the time when the larvae begin to pupa
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
te, the colony again enters the statary phase, and the cycle begins anew (Schneirla, 1971).
Because of the regularity and intensity of E. burchelli and E. hamatum swarms, many insect and bird species have evolved complex relationships with these ants. There are conopid
Conopidae
Conopidae, usually known as the thick-headed flies, is a family of flies within the Brachycera suborder of Diptera. Flies of the family Conopidae are distributed worldwide except for the poles and many of the Pacific islands. About 800 species in 47 genera are described worldwide, approximately 70...
flies (the entire genus Stylogaster
Stylogaster
The conopid genus Stylogaster is a group of unusual flies. It is the only genus in the subfamily Stylogastrinae, which some authorities have historically treated as a separate family Stylogastridae .-Biology:...
) that are obligate associates of army ant raids, and females lay their eggs on insects (mostly cricket
Cricket
Cricket is a bat-and-ball game played between two teams of 11 players on an oval-shaped field, at the centre of which is a rectangular 22-yard long pitch. One team bats, trying to score as many runs as possible while the other team bowls and fields, trying to dismiss the batsmen and thus limit the...
s and roaches
Cockroach
Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...
) flushed into the open by the ants, and there are also some tachinid
Tachinidae
Tachinidae is a large and rather variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. There are over 1300 species in North America. Insects in this family are commonly called tachina flies or simply tachinids...
flies that are somewhat similar in behavior. There are ant-mimicking
Ant mimicry
Ant mimicry is mimicry of ants by other organisms. Ants are abundant all over the world, and insect predators that rely on vision to identify their prey such as birds and wasps normally avoid them, either because they are unpalatable, or aggressive. Thus some other arthropods mimic ants to escape...
staphylinid beetles
Rove beetle
The rove beetles are a large family of beetles, primarily distinguished by their short elytra that leave more than half of their abdomens exposed. With over 46,000 species in thousands of genera, the group is the second largest family of beetles after the Curculionidae...
, shaped like the ants they follow, that run with the swarm, some of them preying on stragglers or other insects injured or flushed by army-ant activity, though most of these are inquiline
Inquiline
In zoology, an inquiline is an animal that lives commensally in the nest, burrow, or dwelling place of an animal of another species. For example, some organisms such as insects may live in the homes of gophers and feed on debris, fungi, roots, etc...
s in the ant nest; these and other insects sometimes spend their entire lives hidden in Eciton colonies, often mimicking the ants or their larvae. Many species of birds—mostly cuckoo
Cuckoo
The cuckoos are a family, Cuculidae, of near passerine birds. The order Cuculiformes, in addition to the cuckoos, also includes the turacos . Some zoologists and taxonomists have also included the unique Hoatzin in the Cuculiformes, but its taxonomy remains in dispute...
s, woodcreeper
Woodcreeper
The woodcreepers comprise a subfamily of sub-oscine passerine birds endemic to the Neotropics. They have traditionally been considered a distinct family Dendrocolaptidae, but most authorities now place them as a subfamily of the ovenbirds...
s, tanager
Tanager
The tanagers comprise the bird family Thraupidae, in the order Passeriformes. The family has an American distribution.There were traditionally about 240 species of tanagers, but the taxonomic treatment of this family's members is currently in a state of flux...
s, and antbird
Antbird
The antbirds are a large family, Thamnophilidae, of passerine birds found across subtropical and tropical Central and South America, from Mexico to Argentina. There are more than 200 species, known variously as antshrikes, antwrens, antvireos, fire-eyes, bare-eyes and bushbirds...
s—feed near the swarms. About 50 of the approximately 200 species of antbirds specialize in preying on insects fleeing the ants, getting up to half their food this way. Some of these birds actively check army-ant bivouacs each morning and follow the foraging trail to the swarm front, where they take positions based on their species' relations in a dominance hierarchy. A swarm may be attended by as many as 25 birds of one or two "professional" species and individual birds of as many as 30 other species. There are even butterflies (esp. the tribe Ithomiini
Ithomiini
Ithomiini is a butterfly tribe in the nymphalid subfamily Danainae. Some authors consider the group to be a subfamily . These butterflies are exclusively Neotropical, found in humid forests from sea-level to 3000 m, from the southwestern United States to Argentina...
) that feed almost exclusively on the feces
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
of these bird species.
Parasites
The miteMite
Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...
Trichocylliba crinita (Elzinga & Rettenmeyer, 1975) (Mesostigmata
Mesostigmata
Mesostigmata is an order of mites belonging to the Parasitiformes. Unlike most members of that group, many of these mites are not parasitic but free-living and predatory. They can be recognized by the single pair of spiracles positioned laterally on the body....
: Uropodidae
Uropodidae
Uropodidae is a family of mites in the order Mesostigmata.-Species:* Allocircocylliba J. F. Marais & G. C. Loots, 1981** Allocircocylliba machadoi J. F. Marais & G. C...
) was found on the jaws of the species Eciton dulcium, and nowhere else.