The life of an ant starts with an egg. If the egg is fertilized, the ant will be female; if not, it will be male. Ants are holometabolous (a specific kind of insect development which includes four life stages) and develop by complete metamorphosis, passing through larval and pupal stages before they become adults.
The larval stage is particularly helpless – for instance it lacks legs entirely – and cannot care for itself. The difference between queens and workers (which are both female), and between different castes of workers when they exist, is determined by feeding in the larval stage. Food is given to the larvae by a process called ‘trophallaxis’ in which an ant regurgitates food previously held in its crop for communal storage. This is also how adults distribute food amongst themselves.
Larvae and pupae need to be kept at fairly constant temperatures to ensure proper development, and so are often moved around various brood chambers within the colony.
A new worker spends the first few days of its adult life caring for the queen and young. After that it graduates to digging and other nest work, and then to foraging and defense of the nest. These changes are fairly abrupt and define what are called temporal castes.
One theory of why this occurs is because foraging has a high death rate, so ants only participate in it when they are older and closer to death anyway. In a few ants there are also physical castes – workers come in a spectrum of sizes, called minor, median, and major workers, the latter beginning foraging sooner.
Often the larger ants will have disproportionately larger heads and so will have stronger mandibles. Such individuals are sometimes called ‘soldier’ ants because their stronger mandibles make them more effective in fighting other creatures, although they are still in fact worker ants and their ‘duties’ typically do not vary greatly from the minor or median workers. In a few species the median workers have disappeared, creating a sharp divide and clear physical difference between the minors and majors.
Most of the common ant species breed in the same way. Only the Queen and breeding females have the ability to mate. Some ant nests have multiple queens. The male ants, called drones, along with the breeding females are born with wings and do nothing throughout their life except eat, until the time for mating comes.
At this time, all breeding ants, excluding the queen, are carried outside where other colonies of similar species are doing the same. Then, all the winged breeding ants take flight. Mating occurs in flight and the males die shortly afterward. The females that survive land and seek a suitable place to begin a colony. There, they break off their own wings and begin to lay eggs, which they care for.
The first workers to hatch are weak and smaller than later workers, but they begin to serve the colony immediately. They enlarge the nest, forage for food and care for the other eggs. This is how most new colonies start.
Worker ants are sterile (do not breed), therefore their jobs are to look for food, protect the eggs, take care of the young, and defend the nest from unwanted visitors. During the night, the worker ants move the eggs and the larvae deep into the nest to protect them from the cold. During the daytime, the worker ants move the eggs and larvae of the colony to the top of the nest so that they can be warmer.
If a worker ant finds a good source of food, it leaves a trail of scent so that the other ants in the colony can find the food. Army Ants are nomadic and they are always moving. They carry their larvae and their eggs with them in a long trail.
Ant Life Span
The average life expectancy of an ant is 45 – 60 days.