Ants are the most numerous type of animal on Earth; their combined weight is greater than the combined weight of human kind.

Ants show maximum diversity in tropical climate zones such as South America, Africa, and eastern Australia but exist many species also in temperate regions of the planet.

Ants, like many other Hymenoptera, are eusocial insects. In their societies, which vary in size and organization according to the species, there is a reproductive class – made up of queens (fertile females) and males – and a working-class made up of sterile females, called workers.

The social organization of ants

The ant society consists of one or more fertile females (queens), males and sterile workers. Queens lose their wings after the nuptial flight and have a pouch organ in which the seminal fluid of several males is collected. The eggs may or may not be fertilized. In the first case, females will develop; in the second one, winged males will develop but die immediately after the copulation. The sterile workers (always wingless) form the core of the colony; at times, several forms differ: macroergates, large ones, microergates, small ones, and dinergates, intermediate, with enormous mandibles.

After the nuptial flight, the fertilized female begins to found a colony, builds a nest with only one chamber, in a suitable place, and lays a first group of eggs; till their hatching, it remains in the nest, and nourishes by reabsorbing wing muscles. The larvae are fed with salivary secretions and give origin to sterile females which begin to operate in the colony: enlargement of the nest, its defense and care, food supply, feeding of the queen and the larvae, etc. After a short time, the winged males and females that are spawned will swarm to form new colonies. Depending on the species, the colony can consist of up to ten to over a million specimens. Sometimes more queens get together to form the nest and constitute polyginic societies. Sometimes there are mixed societies, in which two species live together. 

Ants are social insects living in nests called “anthill” built in different environments and in different ways, shapes and sizes. Such nests can be hypogeal (under the ground) or epigeal (above the ground), in hollows of trees or trunks (like some Camponotus), or built by joining the leaf flaps on the plants.

The underground anthills have various exits and are made up of numerous tunnels leading to chambers of various shapes and sizes which are used for specific purposes such as egg-laying by the queen, feeding the larvae, looking after the pupae, rearing future royals, supplying food, cultivating mycetes for food purposes, etc.

The chambers in which the seeds are collected are covered with a waterproofing secretion produced by the ants to prevent the moisture entering and germinating.

In the social parasitism, the fecundated female gets adopted by an anthill of another species, and leaves when the first daughters have become adult, or gets adopted by a colony without queens, or even penetrates an anthill and kills the queen. In some species (e.g. Anergates), without the caste of the workers, such parasitism is mandatory.

The term dulosis or “slave-making“ indicates the behavior of some species which attack other species and take possession of larvae and pupae which they breed up to the adult stage, in order to be assisted by them. Finally, it can be observed the cohabitation of different species with more or less close symbiotic relationships.

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