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Pharaoh ant

Monomorium pharaonis, Queen surrounded by workers and eggs

Monomorium pharaonis is a very small species of ants. Workers are up to 3.5mm long, while queens (the only fertile females in the colony) 5-6mm.

These insects live in polygyny societies (they contain large numbers of fertile females called queens). These females are successively raised in each healthy nest of eggs and only they lay them. Males or drones are periodically born from unfertilized eggs only when the colony needs them for division or budding. They only serve society to impregnate virgin queens. This process takes place in the nest, mating flights do not take place, which is unique in the world of ants

Young, small colonies raise bigger workers and queens. This is due to the allocation of energy, because a small colony is focused on a rapid increase in the number of sexual individuals, therefore it supplies the queens larvae and some of the workers’ larvae more abundantly with food. In these ant societies, the ratio of queens to worker ranges from 1: 3 to 1:12 and once again a ratio of 1: 3 is for nests of around 300 workers, while a ratio of 1:12 is for those of around 1,500.

Nests are usually established in warm habitats, such as e.g. cracks in walls near heating systems, near water sources, which are actively brought to the nest by the gatherers. They thus increase its humidity.

Workers of this species are completely sterile and the tasks assigned to them are determined by their age. Each healthy nest is full of all developmental stages such as eggs, larvae and pupae. Periodically it becomes too densely populated, which leads to swarms and colony division or the so-called budding.

Budding consists in transferring some members of the colony, including larvae and eggs (without queens), to a place previously considered by workers to be suitable for establishing a nest. Such a “bud”, left without the influence of royal pheromones, raises future young queens from the young larvae provided to it.

Division, on the other hand, consists in passing half or another part of the population to the future nesting site together with the queens.

Monomorium pharaonis, Workers feeding larvae

Queens only live for a year, so they must successively be replaced, as are workers with a maximum lifespan of only 60-90 days. When the colonies reach maturity, they look for suitable places to settle new nests. Newly formed ant families cooperate and share food with others, creating a network of cities connected with each other by communication routes.

Newly formed ant families collaborate and share food with others, creating a network of cities connected with each other by ant communication routes.

At 27 ° C, the entire development period from egg to imago (mature ant) ​​is 39 to 45 days. Queen: egg-11d, larvae-22d, chrysalis-12d total 45 days, worker: egg-11d, larvae-18d, chrysalis-10d total: 39 days. Growth is inhibited as early as 18 ° C and this temperature is lethal for ants. If it takes too long, it will lead to the extinction of workers due to a lack of replacement of generations. The number of degree days for the development of workers is 351 and 405 for queens.

So the development time depending on the temperature in the nest can be calculated from the formula 9 / (T-18) * 39 for workers or 9 / (T-18) * 45 for queens, where T – the average temperature in the nest, the result is given in days). It should be remembered that above 30 ° C, despite the shortening of the development period, there is a steady increase in mortality among eggs and larvae. Above 40 ° C, the mortality is so high that it causes the dying of the colony. The optimal temperature for development is determined in the range of 27-28’C. Any temperature deviation from this point increase mortality and reduces the colony’s productivity.

The Monomorium pharaonis is an omnivorous ant, but for a good colony growth rate it needs animal proteins for the rearing of large amounts of larvae and carbohydrates for adult ants. The best P: C ratio (protein: carbohydrate) is 1: 2 to 1: 4, ants actively regulate this ratio by choosing the right foods for them. Worker ants constantly carry water to the colony, which increases the humidity level and allows them to survive in a dry environment, these ants come from desert and semi-arid areas.

The species range covers almost the entire planet. In tropical and subtropical areas Monomorium pharaonis already occurs naturally, while in temperate climate areas, the spread of the species includes human habitats with additional heat sources in winter and is inherently related to human activity.

These insects are almost blind, but they have retained the ability to perceive light. The first reaction when worried is to look for dark places to hide, but after a while most colonies get used to normal, not overheating light and go about their tasks in a completely normal way.

The ability to orientate in the field results from a very sensitive smell. Ants make routes with pheromones on the ground. Some of them resemble our highways and connect individual ant cities or lead to water and food sources.

See the similarity with honeybees – the genus Apis and other social insects.