Texas Invasive Species Institute

Texas Invasive Species Institute

Pharaoh ant

Monomorium pharaonis

Class: Insecta
Order: Hymenoptera
Family: Formicidae

Monomorium pharaonis

Photographer: Eli Sarnat Affiliation:USDA APHIS ITP Source:www.bugwood.org Copyright: CC BY-NC 3.0

Description

Adult Description: Also known as the sugar ant, the pharaoh ant Monomorium pharaonis has a small body varying from 1/12 to 1/16 inch long (2mm). The workers are monomorphic in size with body coloration varying from golden yellow to reddish-brown, and have a life span of about 70 days. Reproductive males are the same size as the workers but are black in color, and are rarely found in the nest. The queens are 4mm in length and slightly darker than the workers. Queens may live for a year and lay up to 35 eggs per day.

Larva Description: Typical ant larvae. Workers develop from egg to adult in 36 days. Winged males and females require about 44 days to develop.

Host Plant: None

Ecological Threat

The pharaoh ant, much like other invasive species of ants, is able to quickly expand into new territories, and propagate in numbers rapidly enough to overrun and conquer indigenous species. This causes the native species to become displaced from their territory as the invaders lay claim. Thus, species of native ants, such as the carpenter ants and harvester ants, are forced to leave their habitat and find a new one. Therefore, the pharaoh ant causes local extinction of native ants, and, along with other invasive species of ants, can lower the numbers the natives.

Biology

Pharaoh ants form large colonies consisting of many nests. Members move freely between colonies without any antagonism. Colonies vary greatly in size, and some may have only a single queen with a few hundred workers, whereas other colonies may have hundreds of queens with several thousand workers.

In addition to the amiable relationship between different colonies, the formation of new colonies by the process of budding is a major adaptation possessed by the pharaoh ant that allows it to become widley distributed. This is because with budding, a new colony can be formed just from a new queen and a few hundred workers. In fact, a queen does not have to be present as a larva can be taken from the mother colony and formed into a queen for the new colony. This rapid division into further colonies, combined with the subsequent expansion into new habitats allows the pharaoh ant to quickly invade and conquer new areas.

History

The Pharaoh ant, which is probably native to Northern Africa, has become one of the most wide-spread ant species in the world. It was noted as early as 1910 that the pharaoh ant has been carried to all regions of the inhabited world through commerce and trade. The ant is found on all continents except Antarctica. Indeed the pharaoh ant has become one of the more common household ants throughout the world. Further, the pharaoh ant has the dubious distinction of being the household ant that is most difficult to eradicate or control.

Native Origin

Contentious: Probably Northern Africa.

Current Location

U.S. Habitat: Much like the other "tramp" ants, the pharaoh ant is able to nest just about anywhere. They nest inside buildings (homes and greenhouses) and in cracks and crevices. They can also nest between sheets of paper or layers of linens inside houses. This species is also a pest in hospitals and nursing homes.

U.S. Present: The pharaoh ant can be found throughout the United States, especially in the south. As a tropical species, pharaoh ants are weak against colder climates. However, the ants have been found in northern states, nesting within heated buildings. Florida has especially large numbers of Pharaoh ants.

Texas: The pharaoh ant is the most commonly occurring indoor ant in Texas. Chances are if you live in Texas, you have encountered the pharaoh ant either in your own home or at a place of business.

Resembles

Is often mistaken for the Argentine ant, Linepithema humile, due to their similar physical characteristics.

Management

Control of Pharaoh ants is difficult, due to their nesting in inaccessible areas. Treatment must be thorough and complete at all nesting sites, as well as the foraging areas. Thus, treatment must include walls, ceilings, floor voids, and electrical wall outlets. Baits are now the preferred method of control for Pharaoh ants and several baits (insecticides) are labeled for indoor ant control. A Pharaoh ant infestation of a multifamily building requires treatment of the entire building to control the infestation. Ants nesting on the outside may be controlled by also using a perimeter barrier treatment.

References

SEARCH Online

Google Search: Monomorium pharaonis
Google Images: Monomorium pharaonis
NatureServe Explorer: Monomorium pharaonis
Bugwood Network Images: Monomorium pharaonis

References

Beatson SH. 1972. Pharaoh ants as pathogen vectors in hospitals. Lancet 1: 425-427.

Drees BM, Jackman J. (1999). Pharaoh ant. A Field Guide to Common Texas Insects.


TAY, J. W., NEOH, K. B., & LEE, C. Y. 1994. The roles of the queen, brood, and worker castes in the colony growth dynamics of the pharaoh ant Monomorium pharaonis (Hymenoptera: Formicidae). Myrmecol. New 20:87-94.


Wilson GR, Booth MJ. 1981. Pharaoh Ant Control with IGR in Hospitals. Pest Control 49: 14-19, 74.

Internet Sources:

http://www.invasive.org
http://www.issg.org
http://urbanentomology.tamu.edu
http://flrec.ifas.ufl.edu
http://insects.tamu.edu
http://www.entnemdept.ufl.edu

Experts:

Jerry Cook - Sam Houston State University - jcook@shsu.edu

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