Ants

Ants undergo complete metamorphosis—from egg, to larva, to pupa, to adult. Each ant colony begins with, and centers on, the queen, whose sole purpose is to reproduce. Although the queen may copulate with several males during her brief mating period, she never mates again. She stores sperm in an internal pouch, the spermatheca, near the tip of her abdomen, where sperm remain immobile until she opens a valve that allows them to enter her reproductive tract to fertilize the eggs.

The queen controls the sex of her offspring. Fertilized eggs produce females (either wingless workers seldom capable of reproduction, or reproductive virgin queens). Unfertilized eggs develop into winged males who do no work, and exist solely to fertilize a virgin queen. The queen produces myriads of workers by secreting a chemical that retards wing growth and ovary development in the female larvae. Virgin queens are produced only when there are sufficient workers to allow for the expansion of the colony.

Queens live long lives in comparison with their workers and are prolific breeders. A queen of Lasius niger, a common ant found in Europe, lived for 29 years in captivity, while the queen of the urban Pharaoh's ant, Monomorium pharaonis, lives for only three months. The queen of the leafcutter ant from South America produces 150 million workers during her 14-year life span.

The first phase of colony development is the founding stage, beginning with mating, when winged males and virgin queens leave the nest in massive swarms called nuptial flights, searching out a mate from another colony. In colonies with large populations, like that of the fire ant Solenopsis, hundreds of thousands of young queens take to the air in less than an hour, but only one or two individuals will survive long enough to reproduce. Most are taken by predators such as birds, frogs, beetles, centipedes, spiders, or by defensive workers of other ant colonies. A similar fate awaits the male ants, none of which survive after mating.

After mating, queen ants and male ants lose their wings. The queen scurries off in search of a site to start her new nest. If she survives, she digs a nest, lays eggs, and single-handedly raises her first brood that consists entirely of workers. In leafcutter ants, adults emerge 40–60 days after the eggs are laid. The young daughter ants feed, clean, and groom the queen ant. The workers enlarge the nest, excavate elaborate tunnel systems, and transport new eggs into special hatching chambers. Hatchling larvae are fed and cleaned, and pupated larvae in cocoons are protected until the young adults emerge to become workers themselves.

The colony now enters the ergonomic stage, a time entirely devoted to work and expansion. It may take a single season or five years before the colony is large enough to enter the reproductive stage, when the queen ant begins to produce virgin queens and males that leave the nest at mating time to begin the entire cycle anew.

In some species, a new queen founds a new colony alone; in others species, several queens do so together. Sometimes, groups of workers swarm from the nest with a young queen to help her establish her nest. In colonies with several already fertile queens, such as in the Costa Rican army ant Eciton burchelli, entire groups break away with their individual queens to establish individual colonies. In single queen colonies, such as those of the fire ant, the death of the queen means the death of the colony, as she leaves no successors. Colonies with multiple queens survive and thrive.