PHARAOH’s ANT


Monomorium pharaonis

Key features

The workers of this species of ant are only around 2 mm in length, with the queen being larger between 3 and 4 mm long, while the males are around 3 mm. The colouration of the workers is light yellow with a darkish abdomen. The characteristic of the Pharaoh’s ant appearance is the double “waist” known as the pedicel, which in fact constitutes the first segments of the abdomen.

Biology

One of the significant features of the life cycle of the Pharaoh’s ant is the fact that each colony has many nests and also many queens. Each new queen lays around 300 – 350 eggs during her egg-laying spell and the eggs hatch in about a week. The first batch of larvae are tended by the queen while the subsequent generations are looked after by the workers of the colony. Worker ants are able to form satellite colonies, which lead to the spread of infestation. They remove the developing brood from an existing nest and form a new nest elsewhere. By their behaviour towards and feeding of this brood, they are able to produce worker, queen or male ants as required. Males and females are fully winged but they are rarely seen to fly.

Distribution

Originally a tropical ant but will survive in centrally heated locations in temperate regions. Such exotic ants are known as tramp species.
M. pharaonis is the most commonly encountered tramp species in the UK, being found in domestic premises, hospitals, prisons, zoos, botanical gardens, food manufacturing premises etc.

Significance

The multi-nesting behaviour of this species means that if one area of a building is infested, there is the likelihood of extensive spread throughout the building. Areas of high temperature and humidity are favoured by Pharaoh’s ants where they attack human foods such as fruit, jam, sugar, meat, etc. Because of their small size they can be a considerable nuisance in food preparation premises, hospitals, etc. There is evidence that the ant may be involved in the mechanical transmission of some disease-causing agents.

Control

The use of conventional insecticides against Pharaoh’s ants is not recommended as this will almost certainly cause worker ants to form satellite colonies and thus actively spread an infestation deeper into a building.
Granular or gel baits are available for Pharaoh’s ant control. These should be laid where the ants are actively foraging and, particularly with this ant species, treatment of adjacent properties may be advisable.

Illustration:

Monomoreum pharaonis worker ant.

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