Ants usually have distinctly elbowed antennae, in which the first segment is called the scape. It is followed by a series of segments which makeup the funicle. In some species the last two or three segments of the antennae are enlarged, so they are referred to as a club.
The first two or three segment of the abdomen, where it attaches to the thorax, are much smaller than those which make up the rest of the body region, which is called the gaster. This typically gives ants a rather “thin-waisted” appearance. This thin waist is properly known as the abdominal pedicel. The pedicel may consist of one or two segments, and each segment is somewhat enlarged on the upper surface. This enlargement may vary in shape from a slight hump to a rather high, flattened, plate-like structure. When trying to identify ants, it is very important to become familiar with the shape and segmentation of the pedicel, which is sometimes called the “node”. It is an important characteristic used to separate ant species and identify ants from other types of insects.
The mandibles are the most conspicuous of the mouthparts. They are supplied with well-developed musculature and are used to carry and break up food, for excavation of nests in wood or the ground, and as weapons for offense and defense.
Ant antennae are especially important organs because they have many sensory cells and spines. They are particularly important for the senses of taste and touch. Besides their need to detect and taste food, ants are known to use a number of chemical pheromones to communicate between individuals within the same colony. These may be trail pheromones, sex pheromones, alarm pheromones or other types. Many of these pheromones are actually blends of different chemicals and they are deposited or used in very tiny amounts.
Most structure-infesting ants either do not have the ability to sting, or retain it only to a limited degree. A venom is associated with the sting which not only creates rapid, intense pain, but may cause serious allergic reactions in some people.
Ants have a complete metamorphosis, egg, larvae, pupae, and adult. Eggs are almost microscopic in size and vary in shape according to species. Larvae which hatch from the eggs are very soft, pear or gourd-shaped, legless, and off-white in color. The head and the mouthparts are at the narrow end of the body. Adult workers which tend the nest will move the eggs, larvae, and pupae around within the nest, and feed and groom the larvae. After several days to some weeks of feeding, during which time several molts are completed, the larvae will enter the pupal stage. Pupae resemble an adult ant, but are soft, white and do not move about or feed.
Adults require several days to attain complete maturity after emergence from pupae. During this period, the body of the adult hardens and attains mature color. Six weeks to two months or more are required for development from the egg to the adult stage. The time varies according to environmental factors such as temperature, food abundance, disturbances, etc.
Ants live in colonies and have well-developed caste system for the division of labor between adult forms. A newly mated queen digs a gallery to start a nest. The queen seals herself in this cell and remains nearly dormant while the first group of eggs develop in her body. When mature, the eggs are laid and hatch in the sealed cell. Inside her body, the queen’s flight muscles are reabsorbed to provide energy for this long period before workers will be available to forage for food and feed the queen along with the rest of the colony. The queen nurses and feeds the first group of larvae until they pupate. Workers developing from these first eggs are always undersized due to the small food supply which has been available to them. Workers of the first brood dig an opening out of the nest gallery and begin to forage for food, both for themselves and the queen. With an additional supply of food available, the queen is then able to lay more eggs. Workers, which are all sterile females, care fort the new eggs, larvae, and pupae in each succeeding generation.
Successful colonies of many species often take more than one season to develop populations large enough to even be noticed. It will often take one or two years for colonies to develop to the point where substantial numbers of new males and queens are formed. These are usually winged forms called alates, or swarmers, which are capable of reproducing. In some species there may be multiple queens in a mature colony, while others will have only one queen laying eggs. If the queen should die at some time after the colony has become well established, a worker or one of the other female reproductives can sometimes begin to reproduce eggs and take over this function in the colony.
Ant colonies normally have three distinct adult castes – workers, reproductive females (queen) and reproductive males. Workers are sterile females and may vary considerably in size. When all the workers in a colony are basically the same size, the colony is called monomorphic. When different sizes are present, the colony is termed polymorphic. Some workers will have specific tasks due to their specially adapted features.
Queens are generally the largest individuals in the colony. Unmated queens usually retain their wings, while the mated queens do not. After the development of the first group of eggs, the queen is cleaned, fed, and otherwise cared for by the workers, so her primary function becomes egg laying.
Males perform no function other than to inseminate the queen. In those species which have winged queens, males will also have wings. The male dies within a few days of mating. Mating may take place in the nest, on the ground, or in the air. Adult males do not remain in the nest long and many are killed by predators and the elements without mating.
Some ants feed on a wide variety of food items, while others typically feed on a rather narrow range of foods. Food preference may also change significantly during the course of a season, especially for outdoor species, or depending on the specific needs of the colony. Period of high egg reproduction typically require foraging ants to bring back proteins to the queen or queens, while at other times foragers may prefer to gather sugars or greases for their own energy needs or to promote larval growth.
Adults are unable to ingest hard, solid food particles. They ingest only the liquids which are sucked from the food material or smaller particles in suspension. However, they can carry large food items in their mandibles, with or without help from other workers. The youngest larvae must be fed on liquids, and liquid food is used for all larval instars in some species. In many other species, old larvae are fed small food particles which they are able to ingest. Foraging ants bring food or waste back to the colony and pass it to other nest-tending workers by a mouth-to-mouth process called trophollaxis. Nest-tending workers then pass the food to larvae or the queens. Workers may stimulate larvae to regurgitate liquid food, for use within the colony.
In nature, many ants obtain sugar by feeding on the sugary honeydew excreted by aphids or other sucking insects on plants. Some ants tend, and even defend, these other insects as a food resource. Dead insects, earthworms and other organisms are frequently flies and knats will be found on window sills and in light fixtures, so these will be good areas to place ant bait or to apply a residual insecticide spray or dust. Some ants, such as the leaf-cutting ants, actually cut, strip and carry away plant leaf tissue. This leaf material is carried into the nest mound and used as a substrate on which to grow fungi, on which the ant feed. Other ants typically gather seeds as food.
MAJOR PEST SPECIES
Carpenter Ants – These are among the most conspicuous of ants found inCarpenter Ant and around homes, being large and typically blackish or very dark-bodied. Foraging workers have rather large mandibles with which they can bite or give a strong pinch. Workers vary greatly in size, from ¼ to about ¾-inch long. Many species are black, perhaps with some faintly grayish bands on the abdomen; others may have some brown or reddish coloration along with the black so they have a distinctly two-toned coloration.
These ants excavate galleries in wood which somewhat resemble the work of termites, but which can be distinguished by their entirely clean and almost sandpapered appearance. These galleries are frequently hollowed in moist or unsound wood, although carpenter ants can burrow in sound wood. Carpenter ants do not use wood for food, but hollow it out for nesting.
Carpenter ants cut galleries with the wood grain and prefer to follow softer areas of the wood. The galleries are smooth and clean, hence the name “carpenter” ant. Sometimes, the ants cut special openings which are called “windows”.
The occupied galleries are kept very clean. Shredded wood fragments resulting from the excavations are carried from the nest and deposited outside. Conical piles of these wood fragments, bits of soil and sand, portions of insects, dead ants, and other debris sometimes build up beneath the “windows” or other openings to the nest. This “sawdust” is not always evident, however, as the ants may dispose of it in a hollow portion of a tree, void areas in a structure, or unused galleries within the nest. When found during a carpenter ant inspection, this sawdust is often very useful as an aid in locating the nest.
Winged reproductive forms swam primarily in the spring, but may also do so at other times of the year. There is usually only one egg-laying queen per colony. It takes three to six years in most colonies, at which time 2,000 to 3,000 or more individuals will be present, for the winged reproductives or alates to form. From 200 to 400 winged individuals are produced each year in a mature colony.
Foraging ants will travel 100 yards or more from the nest for food, and may wander throughout the house.
Carpenter ants are of economic importance because of the damage they do to structures, the food they contaminate, and their unsightly and unwanted movement inside and outside of buildings. Their nesting activities can weaken building structures, although not usually as seriously as termites. This damage can often be considered primarily a symptom of water damage and wood decay, as they usually will not extend galleries for beyond this softened wood and into the sound wood structures.
Argentine Ant – The argentine ant is a severe pest in the southern United States and in California, although isolated occurrences have been reported in more northern areas.
Workers are 1/12 to 1/8-inch long and are light to dark brown in color. Argentine Ant Queens are much larger, being up to 1/6 to ¼-inch long. Many fertile queens are present in each nest. Mating usually takes place inside the nest, so winged forms are not usually found. In addition to laying eggs, queens also clean and feed themselves, and are active in feeding and grooming immatures.
Nests are typically located in moist soil next to or under buildings, along sidewalks, or beneath boards and plants, and usually near good sources of both water and food. Argentine ants prefer sweet foods, principally sugars, syrup, fruit juices, secretions of plants, and honeydew. Worker forage for food along regular paths extending out from the nest and branching out to explore every portion of an area. Foragers may enter houses in large numbers, particularly when conditions outside the building become too wet or too dry.
Workers are very aggressive and often eliminate other ants in an area. However, different Argentine ant colonies can exist in the same area, so the number of colonies per unit area may be quite high.
Fire Ants – Many of the ants of this genus are called fire ants because theirFire Ant venom, injected by a stinger, causes intense irritation and may cause severe reactions in specially sensitive people. Fire ants are very active and aggressive, and may kill youngwildlife or produce sores and nausea in humans. Four species are commonly found as pest in the United States; the fire ant; the red imported fire ant; the black imported fire ant; and the southern fire ant.
The southern fire ant is found in the southern states, from the Atlantic coast to California. The abdomen is brown to black and usually the head and part of the thorax are yellow to reddish. Workers are 1/15 to ¼-inch long. Nest usually occur in woodwork or masonry of houses. Foragers collect a variety of foods including meat, grease, butter, nuts, seeds, or vegetable.
The fire ant is also found in coastal areas of the southern United States, particularly in Florida. Workers are highly variable in color and have habits similar to those of the other fire ants.
The red imported fire ant is an important agricultural, urban and suburban pest which typically nests in the soil, and makes characteristic earthen mounds. Its presence in lawns, parks, cemeteries, athletic fields and similar areas brings it into direct conflict with people, where its aggressive stinging behavior makes it intolerable in most situations. When mounds of this species are disturbed, workers appear to boil or swarm out of the ground in very aggressive defensive behavior. They will sting any intruding animal repeatedly.
Workers are dark reddish brown in color and may be found in tow basic sizes, called major and minor workers, which are 1/15 to ¼-inch long. Yard may contain one or more mounds and each mound may or may not belong to the same colony. Large colonies can have up to 300-500,000 workers which forage over an area with a radius of over 100 yards. Fire ants are both predators and scavengers, attacking and killing other insects and small animals, or feeding on dead animals. They also feed on honeydew, certain parts of plants or plant secretions, and other sweet materials. Control my be more difficult where more than one queen is present. Colonies have been found nesting and foraging on upper floors on hospitals or other such buildings.
The black imported fire ant is similar to the other three fire ant species in behavior but is a darker brown color. It is now restricted to a small area around the northern end of the border between Mississippi and Alabama. Once quite common in the southern United States but has been displaced by competition from the red imported fire ant.
4. Thief Ant – This is one of the smallest household ants, being from 1/25 to 1/15-inch long. Workers vary in color from yellow to dirty brown, and have a two segmented antennal club. Thief ants are found over most of the United States. They often live in nests of larger ants where they may feed on the larvae of their hosts, thereby earning their common name. In homes their chief foods are greasy materials such as cheese and meats, although they occasionally feed on sweets. Bacon, ham and other prepared meats are especially attractive to thief ants. They may feed on stored seeds and dead animals.
This ant is so small that it may often escape notice around kitchen sink and cabinet areas. Unobservant people may complain about the flavor of the food without realizing that it is infested with thief ants. The ant usually comes in from outdoors, but may nest in cracks and crevices of walls or cabinets and commonly beneath tile and countertops in kitchens. They are very persistent and may be quite difficult to control.
Pharaoh Ant – Pharaoh ants are light yellowish to reddish-brown inPharaoh Ant color, with workers measuring 1/15 to 12/-inch long. They are found in localized regions throughout the United States and parts of southern Canada. They have become a common pest in many areas and an important source of business for pest management firms. Pharaoh ants can be easily distinguished from thief ants by the presence of three segments in the antennal club. They are an important pest in homes, apartments, hotels, grocery stores, restaurants, hospitals, nursing homes and other facilities throughout much of their range.
Nest are rarely found, but occur between walls, under floors, above ceilings, behind baseboards and switch plates, in old trash, in folded bathroom linens, or outside in gardens and along walks. Pharaoh ants nest in porous substrates in warm places near furnaces, heat ducts, and hot water pipes which are also near moist conditions or open sources of water. Nests are very difficult to find since the ants forage widely from them, usually over established trails marked by trail pheromones. Workers are frequently seen trailing along window sills, counter tops, and baseboards.
They will feed on such a diverse array of materials that use of the term “food preference” seems inappropriate. However, substances like syrups, fruit juice, hone, jelly, cakes, pies, greases, dead insects, or meats and blood are frequently fed upon.
Pharaoh ant colonies may be very large, with tens of hundreds of thousands of workers, and many queens. Moderate-to-large-sized colonies will frequently bud to form numerous subcolonies, as a queen or queens and a group of workers (carrying brood) will move away from the larger colony and begin a new colony unit.
The mature sexual forms (males and females) are winged but do not fly, so swarms are never seen. Mating occurs in the nest, throughout the year. Occasionally, when a particularly good food source is found, especially close to the nest, some queens can be seen traveling to and from the food location.
Little Black Ant – This is a very small (1/15-inch long), jet blackLittle Black Ant colored ant found in all states. Nests are normally located outdoors in relatively open areas. These ants will also nest in rotten wood, wood-work, and masonry of buildings. Colonies may become very large. Most of their feeding is on plant secretions, but they will occasionally invade houses for food. They will then feed on sweets, meats, bread, grease, vegetables and fruit.
Big-headed Ants – The soldiers (workers which serve a strictlyBig Headed Ant defensive function) of these ants have exceptionally large heads in relation to their body size. The minor workers do not have enlarged heads but can be recognized by the shape of their heads, which narrow abruptly behind the eyes. They are found in warmer and dryer sections of the United States, and have very similar habits to fire ants. Nests are founding exposed soil or under cover, and in rotting wood. Rarely nest indoors but may invade homes to forage for food. They prefer meats, greases, and breads. Have 12 segments in the antennae, with a 3-segmented antennal club.
Pavement Ant – This is a small (1/8 to 1/16-inch long) blackish-brownPavement Ant ant, with paler legs and antennae. Readily visible on the head and thorax are parallel lines or ridges, which do not differ in color from the cuticle, but give the cuticle a lined texture. There is a pair of small spines at the back of the thorax, and the body has sparse array of small hairs all over it.
This ant is an occasional pest in the southern United States. Nests are usually found outdoors under stones, next to buildings and under cracks of pavement, although they are occasionally found in walls, under floors, and in insulation. This slow moving ant enters buildings in search of food, with greasy and sweet materials being preferred.
Little Fire Ant – This small tropical ant has been established in FloridaLittle Fire Ant and in California. It is about 1/15-inch long, reddish in color, and characteristically moves around very slowly. These ants are very sensitive to cold, appearing only in the warmest weather. Their sting is very painful.
Little fire ants are a serious household pest, contaminating food and infesting unlaundered clothing and beds. They nest in exposed or covered soil, rotten wood, plant cavities, trash, and occasionally in houses. In the house, they prefer foods such as fats, peanut butter and other oily materials.
Harvester Ants – These are comparatively large, red to dark- brown ants which range from ¼ to ½-inch long. Long hairs form a “brush” under their heads. These hairs are used to clean their legs and antennae, carry water and remove sand during excavation of the nest. Harvester ants are found in warmer and dryer regions of the East and South. They are normally found in fields or in laws, and only rarely invade the home. Their severe stings make them pest when they occur in lawns. They clear large areas of vegetation around their nest openings and gather seeds which they store in their burrows.
Leaf-cutter Ants – These ants remove foliage from vegetation and carry ti back to the nest. Leaf fragments are chewed and added to large underground fungus gardens which provide the colony’s food. In the United State, leaf-cutter ants occur in Texas, Louisiana and Arizona. The length of the workers ranges from 1/12 to ½-inch, and they are dark brown or rust colored. The dorsal part of the thorax has at lease three pairs of spines.
Acrobat Ants – Ants of this genus hold their abdomen over their head or thorax when excited. They are yellowish-brown or black, with a heart-shaped abdomen which is flattened on the upper side and curved below. They are not usually found in households, but may wander inside from time to time in search of food. Some species in this genus may be found in decayed or partially decayed wood. They are seldom found in sound wood.
Odorous House Ant – This is a very common household ant pest species which is distributed nearly throughout the United States. Workers are 1/12 to 1/8-inch long and brownish-black in color. This ant is frequently confused with the Argentine ant, but can be easily distinguished by its darker color and the fact that the front of its abdomen overhangs and hides the petiole. When crushed, this ant gives off a very unpleasant odor.
Outside nests are usually shallow and found underneath a board or stone. Indoor nest are frequently found in walls and underneath floors. Colonies are large and each may contain several active queens. Workers forage along regular trails. The food habits of odorous house ants and Argentine ants are similar. Odorous house ants tend to move indoors late in the year when honeydew, one of their primary foods, is less abundant. Honeydew availability may also be reduced at other times, such as during and just after periods of excessive rainfall.
Velvety Tree Ants – They are easily identified by their glistening, velvety-black abdomen, red thorax and brownish-black head. Their nests are located in old tree stumps, cavities in trees, under tree bar, beneath stones on the ground, and occasionally within the walls of attics of homes. Foragers commonly enter homes, where they contaminate foods in the kitchens and seek other insects for food.
Their bite is quite painful and the pain may persist for some time.
Pyramid Ants – These ants are common in the southern United States and in California. They vary in color from uniformly dark brown to brown with a reddish tint. Workers have a distinct single tooth on their thorax, which causes the thorax to form a pyramid shape. Workers are 1/15 to ½-inch long and are commonly found in gardens and flower beds. They often tend aphids on ornamental plant, feeding on honeydew, but also frequently enter homes along distinct foraging trails.
Field Ants – The many species and varieties of these ants infest fields, lawns, and gardens throughout the United States. Their length varies from 1/8 to ¼-inch and they may be brown, black, reddish, or have combinations of these colors. Foragers prefer sweet foods, and also feed on other insects.
Field ants are most likely to be pests of recreational areas. When infestations are heavy, individuals may wander into homes in search of food.
Some field ants capture the larvae and pupae of other ants and raise them in their own nests. The emerging adults become slave to the field ants. Thus, field ants are sometimes called slave ants.
Crazy Ant – This ant is found in scattered locations in all states.Crazy Ant Workers are about 1/10-inch long and dark brown in color. Their legs and antennae are much longer than normal from other ants, in proportion to the other parts of their body. These unusual features are good identifying characteristics.
The crazy ant cannot survive outdoors during cold winters. Its habit of running aimlessly about the room accounts for its name. Crazy ants nest in small cracks, crevices and voids inside, and wander throughout the building searching for food. They prefer to feed on animal matter, grease, and other insects, but will readily eat sweets of all kinds.
False Honey Ant – This ant is widely distributed throughout the United States. The shiny workers vary in color from light to dark brown and are about 1/8 to 1/6-inch long. They typically nest in clay soils in well-shaded areas. The nest entrance is usually surrounded by coarse earthen pellets. Within the nest, certain false honey ant workers are fed large quantities of sugary liquids by other workers. They store this in their greatly distended abdomens and regurgitate to other ants as required.
Cornfield Ant – It is common in cornfield. In homes, it prefers sweet substances. It also feeds on dead and live insects, plant sap, and honeydew. Common nesting sites include rotting logs, stumps, under stones, and in exposed soil, but seldom in houses. It often builds small craters in lawns. This ant is the most common “picnic” ant in its range.
Large Yellow Ant – Common from New England to the Midwest, is known as the critronella ant because of the odor given off when crushed. Workers are reddish-brown color and about 1/5-inch long. Winged reproductives swarm in basements and around house foundations in early spring, and are frequently mistaken for termites. Outdoor nests are found in logs, stumps and under stones. This ant may bring large piles of dirt to the surface of the ground at the entrance to its nest, either outdoors or indoors. Aside from the debris created, no harm is done by this ant. Foragers prefer sweets, but have not been reported utilizing human foods.