Of all the ant species that are regular or casual household pests, the pharaoh ant is, along with the carpenter ant, the most persistent and difficult to control!

Monomorium pharaonis (L.)

Pharaoh ants are social insects that are easily distinguished from other insects because their body regions are distinctly defined by very narrow attachments.

The pharaoh ant is an introduced pest and is native to the tropics of Africa, but has spread throughout the world.  The life cycle, feeding habits, foraging behaviour, colony size, and distribution patterns of this tiny ant all contribute to its pest status.  In some locations, particularly hospitals, food service establishments and apartment buildings, pharaoh ants are the most serious pest alongside the cockroach.  Elimination must be the objective because control is usually not adequate or acceptable.

The pharaoh ant is very small, one eighth of an inch long and varies from yellow to reddish-brown in colour.  The narrow waist has two segments and the clubbed end of the antennae have three segments.  Pharaoh ant colonies may be fragmented and widely dispersed throughout a structure.  Colonies can contain as many as half a million workers and thousands of queens (egg-producing females).  Males are produced only periodically but swarms of winged males and females are not common. Frequently, mating takes place in the nest, and the formation of a new colony occurs when queens and workers carry eggs and other immature stages of the ant to a new location. New colonies can be established with one fertilized queen, five workers, and 20 immature stages.  Recently formed colonies may not forage for several days, but soon make new trails and look for food.  Nests may be located outdoors in the lawn or garden, or indoors behind walls (in wall voids), in attics, behind paneling, and in furniture or machinery.  These ants are frequently found in kitchens, bathrooms, or other rooms with accessible water and warm temperatures-although their nest sites are dry.

Pharaoh ants feed on dead or live insects, and seem to prefer meats or greases.  They also eat sugar syrup, fruit juices, jellies and cakes.  In hospitals they have been found on open wounds and often infest the dressings on patient's wounds. their small size, foraging behaviour, and feeding habits, make the pharaoh ant difficult to control because they can nest in such a wide variety of locations within a structure.  Since they do not follow specific trails to food sources, it is extremely difficult to trace a trail to their nests.

More facts about pharaoh ants:

• On all ants the abdomen is attached to the thorax (the segment bearing the legs) by a slender one or two segmented attachment called a petiole. Pharaoh ants have two bumps called nodes, on their petioles and they have a three segmented club at the end of their antennae.  For more about ant anatomy go back to Ants
• Pharaoh ants do not swarm.  The males and females mate in the nest, and new colonies are formed by "budding" in which part of the main colony moves en masse to a new location.
• A female pharaoh ant can produce 350 to 400 eggs in its lifetime.  The eggs hatch in five to six days, the larvae develop in 22 to 24 days and the pupal period lasts 9 to 12 days.
• The maximum life for a worker ant is 9 to 10 weeks
• An egg-producing female (queen) lives for about 40 weeks.
• Male pharaoh ants live for only about 3 weeks.