Pharaoh ant

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Pharaoh ant

Scientific classification

Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Genus:	Monomorium
Species:	M. pharaonis

Binomial name

Monomorium pharaonis
(Linnaeus, 1758)

Synonyms

Formica pharaonis

The pharaoh ant (Monomorium pharaonis) is a small (2 mm) yellow or light brown, almost transparent ant known for being a major indoor nuisance pest, especially in hospitals. The origin of this 'tramp' ant is uncertain, although favoured alternatives include West Africa and Indonesia. The Pharaoh ant has been introduced to virtually every area of the world including Europe, the Americas, Australasia and Southeast Asia. Pharaoh ants are a tropical species but they thrive in buildings anywhere, even in temperate regions provided central heating is present.

Unlike most ants the Pharaoh ant is polygynous, meaning its colonies contain many queens (from 2 to over 200). An individual colony normally contains 1000 - 2500 workers but a high density of nests gives the impression of massive colonies. Colonies also lack nestmate recognition so there is no hostility between neighbouring colonies. Pharaoh ants lack the normal cycle of reproduction observed in most ants; they are able to produce sexual reproductive individuals as required. Laboratory colonies exhibit weak reproductive cycles but this cannot be assumed to be the natural condition. Colonies reproduce by 'budding', where a subset of the colony including queens, workers and brood (eggs, larvae and pupae) leave the main colony for an alternative nest site. Budding is the major factor underlying the invasiveness of Pharaoh ants. A single seed colony can populate a large office block, almost to the exclusion of all other insect pests, in less than six months. Elimination and control are made difficult because multiple colonies can also contract into smaller colonies and 'weather the storm' of a baiting programme only to rebound when baiting is withdrawn. Pharaoh ants are a major hazard in hospitals, where their small size means they can access wounds, driplines, and instrumentation, causing spread of infection and electrical interference.

Pharaoh ants have become a serious nuisance pest in hospitals, rest homes, apartment dwellings, hotels, grocery stores, food establishments and other buildings. They feed on a wide variety of foods including jellies, honey, shortening, peanut butter, corn syrup, fruit juices, baked goods, soft drinks, greases, dead insects and even shoe polish. Also, these ants gnaw holes in silk, rayon and rubber goods. In hospitals, foraging ants have been found in surgical wounds, I.V. glucose solutions, sealed packs of sterile dressing, soft drinks, water in flower displays and water pitchers. These ants are capable of mechanically transmitting diseases and contaminating sterile materials. Some feel Staphylococcus and Pseudomonas infections, occurring from time to time in hospitals, are associated with these ants.

1 Identification
2 Life Cycle and Habits
3 References
4 External links

[edit] Identification

Pharaoh workers are very small (about 1/16-inch long, or 2.0 milimeters), light yellow to reddish brown in color with the abdomen (hind portion of body) somewhat darker. There is a stinger. The petiole (narrow waist between the thorax and abdomen) has two nodes and the thorax has no spines. Eyes are poor and possess on average 32 ommatidia. The antennal segments end in a distinct club with three progressively longer segments.

[edit] Life Cycle and Habits

Female Pharaoh ants can lay 400 or more eggs in her lifetime. Most lay 10 to 12 eggs per batch in the early days of egg production and only four to seven eggs per batch later. At 80°F (27°C) and 80 percent relative humidity, eggs hatch in five to seven days. The larval period is 18 to 19 days, prepupal period three days and pupal period nine days. About four more days are required to produce sexual female and male forms. The entire life cycle takes about 38 to 45 days depending on temperature and relative humidity. Unlike most ants, they breed continuously throughout the year in heated buildings and mating occurs in the nest. A single queen can produce many hundreds of workers in a few months. Mature colonies contain several queens, winged males, sterile females or workers, eggs, larvae, prepupae and pupae growing to as large as 2,500 or more members. Unicoloniality means that contiguous colonies can give the impression of massive colony size, when in fact one is observing a supercolony which may contain many hundreds of thousands of individuals from dozens of smaller, separate colonies.

Pharaoh ants engage in a behavior pattern known as "satelliting," "fractionating" or more usually "budding". Part of the colony migrates to a new location, which contrasts with the more common mechanism of colony reproduction where single females disperse and independently found colonies after a reproductive swarm. A queen together with a few workers carrying immatures (eggs, larvae and pupae) leave the nest and set up a new colony elsewhere. Budding is a major factor in the rapid spread of infestations.

Nests can be very small for example, located between sheets of paper, in clothing or laundry, furniture, foods, etc. Nests usually occur in walloids, under floors, behind baseboards, in trash containers, under stones, in cement or stone wall voids, in linens, light fixtures, etc. They prefer dark, warm areas near hot water pipes and heating tapes, in bathrooms, kitchens, intensive care units, operating rooms, etc. They are "trail-making" ants and often are found foraging in drains, toilets, washbasins, bedpans and other unsanitary sites as well as in sealed packs of sterile dressing, intravenous drip systems, on surgical wounds, food and medical equipment.