Carpenter ants are large (¼–1 in) ants indigenous to many parts of the world. They prefer dead, damp wood in which to build nests. Sometimes carpenter ants will hollow out sections of trees. The most likely species to be infesting a house in the United States is the Black carpenter ant, Camponotus pennsylvanicus. However, there are over a thousand other species in the genus Camponotus.
Carpenter ant species reside both outdoors and indoors in moist, decaying or hollow wood. They cut "galleries" into the wood grain to provide passageways for movement from section to section of the nest.
Carpenter ants can damage wood used in the construction of buildings. They can leave a sawdust like material behind that provides clues to nesting location.
Odorous House Ant
Tapinoma sessile is a species of ant that goes by the common names odorous house ant and coconut ants.
This species is a scavenger/predator ant that will eat most household foods, especially those that contain sugar, and other insects. Indoors they will colonize near heat sources or in insulation. In hot and dry situations, nests have been found in house plants and even in the lids of toilets. Outdoors they tend to colonize under rocks and exposed soil. They appear, however, to form colonies virtually anywhere, in a variety of conditions. They can trail extensive distances (though their trails are rarely longer than 50 feet), usually along landscape edges. Colonies range in size from 100-10,000, and house several queens (as many as 200, in some instances). They are non-aggressive. While queens can lay as many as 20-30 eggs in single day, they lay only 1-2 (or less) eggs per day on average over long periods of time. Typical time to adult phase of development is 34-38 days. It is believed that queens and male ants are only produced in larger colonies.
In experiments where T. sessile workers were confined in an area without a queen, egg-laying (by the workers) was observed, though the workers destroyed any prepupa that emerged from the eggs. Odorous house ants have been observed collecting honeydew to feed on from aphids, scale insects, and membracids. They appear to be more likely to invade homes after rain (which washes away the honeydew they collect). Odorous house ants appear to be highly tolerant of other ants, with compound nests consisting of multiple ant species (including T. sessile) having been observed.
They range in colour from brown to black and range in length from 1/16 to 1/8 inches ( 1.5 - 3.2 mm). Their antennae have 12 segments.
Little is known about the lifespan of the ant, though it has been shown that queens can live at least 8 months (and probably much longer), workers at least a few months (and show every indication of living as long as queens), and males appear to live only approximately a week.
The odorous house ant is very tough, and injured workers have been observed to continue living and working with little hindrance. Some queens with crushed abdomens could still lay eggs, and there are documented instances of T. sessile queens surviving without food or water for over two months. They also appear highly tolerant to hot and cold temperatures. These ants are very resistive and can resist over heavy blows as well. These ants are tough to remove from the body and leave an odorous smell as well.
Predators and Parasites
Wheeler (1916) mentions Bothriomyrmex dimmocki as a potential parasite of oderous house ant colonies (suggesting that B. dimmocki queens invade and replace T. sessile queens).
Isobrachium myrmecophilum (a small wasp) appears to parasitize odorous house ants.
Some birds and toads will also eat odorous house ants on occasion.
Origin of common names
The common names "odorous house ant" and "coconut ant" come from the odor the ants produce when crushed, which is very similar to the pungent odor of a coconut.
These ants are not hard to control, and most ant killers will solve problems, especially if controlled as soon as the problem is noticed. At this point, they could be put under control in just a few days. However, the longer someone waits, the larger the population is and the longer it will take to control the situation, possibly a few weeks. Standing water should be eliminated, as odorous house ants are attracted to moisture. Plants should be trimmed back so they cannot be used to get inside. Cracks, holes and joints should be sealed with polyurethane foam or caulk, especially those that are near the ground. Firewood, rocks and other materials should not be stored next to a home because it encourages nest building. People should be on the lookout for these ants in late winter and early spring (particularly after rain), as this is when they most commonly appear.
The pavement ant, Tetramorium caespitum, is a common household pest. Their name comes from the fact that they usually make their homes in pavement. They are distinguished by two spines on the back, two nodes on the petiole, and grooves on the head and thorax.
During early spring, colonies attempt to conquer new areas and often attack nearby enemy colonies. These result in huge sidewalk battles, sometimes leaving thousands of ants dead. Because of their aggressive nature, they often invade and colonize seemingly impenetrable areas. In summer time the ants dig out the sand in between the pavements to vent the nests.
The pavement ant is dark brown to blackish, and one-eighth inch long. It will eat almost anything, including insects, seeds, honeydew, honey, bread, meats, nuts, ice cream and cheese. The species does not pose a public health risk, but can contaminate food and should be avoided.
These ants are easily controlled with the use of sugar baits laced with borax (boric acid).
The pharaoh ant (Monomorium pharaonis) is a small (2 mm) yellow or light brown, almost transparent ant notorious 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.
The Pharaoh ant is polygynous, meaning its colonies contain many queens (up to 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, which is known as unicoloniality. They produce sexually reproductive individuals roughly twice a year in established colonies but in the laboratory colonies can be manipulated to produce sexuals at any time of year. Colonies proliferate 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 a 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 consolidate into smaller colonies and "weather the storm" of a baiting programme only to repopulate 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 the spread of infection and electrical interference.
Pharaoh ants have become a serious 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. They can also gnaw holes in silk, rayon and rubber goods.
Pharaoh workers are about 1/16-inch long, or 2.0 millimeters in length. They are light yellow to reddish brown in color with a darker abdomen (hind portion of body). 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.
Life Cycle and Habits
The pharaoh ant queen can lay hundreds of 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. From egg to maturity takes about 38 to 45 days depending on temperature and relative humidity. They breed continuously throughout the year in heated buildings and mating occurs in the nest. Mature colonies contain several queens, winged males, workers, eggs, larvae, prepupae and pupae.
Pharaoh ants engage in a behavior pattern known as "satelliting", "fractionating", or, more commonly, "budding". Part of the colony migrates to a new location. Nests can be very small, 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.
Pharaoh ants have been exterminated by placing baits, consisting of ground liver mixed with boric acid, in places where the ants forage. Renewing the baits once or twice may be necessary. It is recommended not to exterminate using sprays and dusts because they will cause the pharaoh ants to scatter.