Pest Information - Ants

There are almost 9,000 species of ants and they can be found from the Arctic Circle to the Tropics. This site will focus on the ants most commonly found in Hawaii. Learn about their Appearance, Habitat, Diet, Type of Damage, and Life Cycle.
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Pharaoh Ant

Scientific Name

Monomorium pharaonis

Appearance

Pharaoh workers are very small (about 1/16-inch long), light yellow to reddish brown in color with the abdomen (hind portion of body) somewhat darker. There is no stinger. The petiole (narrow waist between the thorax and abdomen) has two nodes and the thorax has no spines. Eyes are well-developed. The antennal segments end in a distinct club with three progressively longer segments. This is in contrast to the thief ant's two-segmented club.

Habitat

Pharaoh ant nests are often so small it can be contained in a thimble, located between sheets of paper, in clothing or laundry, furniture, foods, etc. Nests usually occur in wall voids, 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.

Diet

Pharaoh ants 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.

Type of Damage

Pharaoh ants have become a serious nuisance pest in hospitals, rest homes, apartment dwellings, hotels, grocery stores, food establishments and other buildings. Pharaohs gnaw holes in silk, rayon and rubber goods. These ants are capable of mechanically transmitting diseases and contaminating sterile materials.

Life Cycle

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 and 80 percent relative humidity, eggs hatch in 5 to 7 days. The larval period is 18 to 19 days, prepupal period 3 days, and pupal period 9 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 300,000 or more members. Periodically, a queen, together with a few workers carrying immatures (eggs, larvae and pupae) leave the nest and sets up a new colony elsewhere, quickly spreading an infestation. This behavior pattern is known as "satelliting," "fractionating", or "budding" where part of the colony migrates to a new location rather than by single females dispersing after a reproductive swarm. Budding may occur due to overcrowding, seasonal changes in the building's central heating and cooling system or application of a repellent pesticide.

Interesting Facts

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. Some feel Staphylococcus and Psuedomonas infections, occurring from time to time in hospitals, are associated with these ants.