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Monomorium pharaonispharaoh ant

By Daniel Morris

Geographic Range

The Pharaoh ant is limited by cool climates, and relies upon humans for a suitable home in northern regions. This ant originates in the Old World tropics of Africa and has migrated to areas acrss the globe. (Klots and Klots, 1959)

Habitat

The diversity of habitats the Pharaoh ant can live in is amazing! In Northern climates however, their nests often occur within households--the spaces in walls between the studs and insulation offer warm breeding grounds relatively hidden from our [human] eye (Howard, 1908). A major nuisance in the United States, the Pharoah ant is small, and difficult to gauge in population size. Their colonies are ruined by sealing cracks, and cutting off exposure to food. Kerosene has historically been used for this purpose (Klots and Klots 1959). (Howard, 1908; Klots and Klots, 1959; Howard, 1908; Klots and Klots, 1959)

Physical Description

Definitely one of the smallest ants at a mere 1/12 or 1/16 of an inch, their bodies are reddish brown to slightly tan in nature (Drees and Jackman 1998). Each compound eye has 20 facets, and each mandible has four teeth. Paired longitudinal and metanotal grooves are definitely distinct. The prodpodeal dorsum has no "standing hairs" (Ogata, et al 1998).

Pharoah ants (like all insects) have three main body sections: thorax, head, and abdomen, and three pairs of jointed legs that are attached to the thorax. Pharaoh ants use their antennae to sense vibrations, and for aiding vision in non-lighted areas. Small hairs that may be present on the abdomen can aid in sensing the weather, or by processing touch. Finally, like all arthropods, they contain a hard exoskeleton and additionally have a waxy cuticle to prevent drying out. Arthorpod skeletons are made of chitin, a polymer derivative of starch similar to our fingernails (Raven and Johnson 1999). (Drees and Jackman, 1998; Ogata, et al., 1998; Raven and Johnson, 1999)

  • Sexual Dimorphism
  • female larger
  • Range length
    1 to 2 mm
    0.04 to 0.08 in

Development

5 to 6 days after being laid, Monomorium pharaonis eggs hatch into larvae. Larvae grow and develop over 22 to 24 days, passing through several instars “growth phases which end with molting). When the larvae are ready, they enter the pupal stage to undergo complete metamorphosis that is complete 9 to 12 days later. The pupal stage is the most vulnerable to environment and predators. The pupae are relatively inactive, and do not eat. Therefore, adult ants take a total of 38-45 days to fully mature, while another 4-5 days are required for sexual forms to reach maturity.

As the larvae grow, they must molt to a larger stage or instar. Molting is regulated by the molting hormone, ecdysone. This hormone is released by a gland located in the thorax, which is stimulated by the "brain hormone" produced by neurosecretory cells. Another hormone called juvenile hormone is most abundant in immature stages of the ant, and decreases with the passing of each stage toward adulthood. (Raven and Johnson, 1999)

Reproduction

Pharaoh ants have copulatory organs for internal fertilzation. After the new queen has mated with at least one male (sometimes more) she will store the sperm in her spermatheca so that she can use it to fertilize all of her eggs throughout the rest of her life.

Like most ants, sexual castes (those capable of reproduction) copulate in a “nuptial flight”. This is when environmental conditions are favorable to encourage mating and males and virgin queens fly into the air at the same time in order to find mates. After a short while the males die, and the queens lose their wings and find a place to begin her colony. (Raven and Johnson, 1999)

After a queen mates, she will found a new colony. This means that she will lay eggs and care for the first brood herself. After the first generation mature, they will care for the queen and all future generations as the colony grows. In addition to the founding of a new colony by a newly mated queen, colonies may also “bud”. This is where part of an existing colony carries brood to another "new" nesting site along with a new queen --often a daughter of the parent colony’s queen. (Drees and Jackman, 1998)

After a queen mates, she will found a new colony. This means that she will lay eggs and care for the first brood herself. After the first generation mature, the new workers will care for the queen and all future generations as the colony grows. (Drees and Jackman, 1998)

Behavior

Like other hymenoptera, the pharoah ant has a haplo-diploid genetic system. This means that when the female mates, she stores the sperm. As eggs move down her reproductive ducts, they can either be fertilized, becoming a diploid female, or not fertilized, becoming a haploid male. Because of this unusual system, females are more closely related to their sisters than they are to their own offspring. This may explain the presence of female workers. The workers include food gatherers, "babysitters" of the developing eggs, and guardsmen/look outs for the nest.

The nest of a Pharaoh ant contains workers, queen or queens, and male/female winged ants. The workers are female and sterile while the males tend to only be winged, with a main function of reproduction. The female and male ants that are winged also provide general protection for the nest. The queen becomes a mechanical egg layer for her extended life time. Losing her wings an average of five days after mating, the queen quickly settles down to egg-laying. (Crozier and Pamilo 1996)

Communication and Perception

Pharaoh ants communicate through tough and chemical markers called pheremones. They are have very good eye sight and can sense vibrations of potential predators or movement from their own larvae.

Food Habits

The Pharaoh ant is omnivorous and their broad diet is reflective of their tolerance of diferent habitats. Pharaoh ants feed on sweets: jelly, sugar, honey, cakes, and breads. They also enjoy greasy or fatty foods such as pies, butter, liver, and bacon. Believe it or not, a preference of freshly used medical bandages attracts these ants to hospitals. These ants may find also their way into your shoe polish. In their natural environment, Pharaoh ants may be found enjoying a recently deceased insect such as a cockroach or a cricket. Pharoah ants use chemical trails laid down by other workers in order to find food. (Drees and Jackman, 1998)

  • Animal Foods
  • eggs
  • body fluids
  • carrion
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • seeds, grains, and nuts
  • fruit
  • nectar
  • sap or other plant fluids

Predation

Since these ants are so small, little is known about the predators of this species.

Ecosystem Roles

Little is known on the effects these ants have on their native environment. In areas where they have been introduced they are considered to be a household pest.

Economic Importance for Humans: Positive

Monomorium pharaonis removes and feeds upon crumbs and bits of food left unattended. Living with humans, these insects do not swarm as other ants, and they limit other household pests such as cockroaches by eating the leftover, exposed food supply.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Because of their attraction to soiled bandages, hospitals must limit patient exposure to this pest. The microscopic bacteria that these ants can carry is sometimes pathogenic, including Salmonella, Pseudomonas, Clostridium, and Staphylococcus. Also Pharaoh ants can annoy home owners by congregating on food and dishes left unattended. (Drees and Jackman, 1998; Drees and Jackman, 1998)

Conservation Status

There is no special status for this ant.

Other Comments

The Pharoah ant may be confused wtih the Thief ant. This ant is similar in physical characteristics, except has a more yellow tint to its body. Also, the foods eaten by this ant are similar to those of the Pharoah ant. College campuses are excellent breeding grounds for the Pharoah ant, especially the kitchen or dormitories. (Klots and Klots 1959)

Contributors

Sara Diamond (editor), Animal Diversity Web.

Daniel Morris (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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Neotropical

living in the southern part of the New World. In other words, Central and South America.

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Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carrion

flesh of dead animals.

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

delayed fertilization

a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

eusocial

the condition in which individuals in a group display each of the following three traits: cooperative care of young; some individuals in the group give up reproduction and specialize in care of young; overlap of at least two generations of life stages capable of contributing to colony labor

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

internal fertilization

fertilization takes place within the female's body

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

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pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

References

Crozier, R., P. Pamilo. 1996. Evolution of Social Insect Colonies: Sex allocation and Ken Selection. New York, New York: Oxford University Press Inc..

Drees, B., J. Jackman. 1998. A feild Guide to Common Texas Insects. Houston, Texas: Gulf Publishing Company.

Greensmiths, January 2000. "Pharaoh Ants" (On-line). Accessed April 15, 2000 at http://www.greensmiths.com/pharaoh.htm.

Grzimek, B., J. Liebig. 1972. Grzimek's Animal Life Encyclopecia: Volume 2, Insects. New York, New York: Van Nostrand Reinhold Company.

Howard, L. 1908. The Insect Book. New York, New York: Doubleday, Page & Company.

Klots, A., E. Klots. 1959. Living Insects of the world. Garden City, New York: Doubleday & Company Inc..

Ogata, K., M. Terayama, R. Taylor. 1998. "Japanese Ant Database Group" (On-line). Accessed April 14, 2000 at http://taxa.soken.ac.jp/ANT.WWW/Taxo_E/F41107.html.

Raven, P., G. Johnson. 1999. Biology, 5th Edition. New York, New York: WCB McGraw-Hill.

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