Introduction to Ant

Ant, a small insect. Ants are noted for the complex societies in which most of them live. They are often cited as symbols of thrift and industry, because many species seem tireless in their activity and store large quantities of food. The study of ants has appealed to naturalists since ancient times. Children often keep ant colonies to observe their activities. Ants are found in nearly all parts of the world except the polar regions.

Ants that live underground create tunnels that permit air to circulate through the soil, thereby making the soil more productive and benefiting agriculture. Some kinds of ants kill certain insect pests that feed on crops. Many kinds of ants are themselves pests; they invade houses and warehouses in search of food, and can destroy plants, including crops. Chemical insecticides are used to kill ants.

AntsAnts are small, six-legged insects that can grow up to two inches long.

Description

Body

Ants vary in length from about 1/16 inch (1.6 mm) to nearly 2 inches (5 cm). Most species are red, black, brown, or yellow, and some are green or metallic blue. Ants, like other insects, have six legs. Their bodies are divided into three distinct segments: head, thorax, and abdomen. Unlike other insects, ants have elbowed (rather than straight or curved) antennae (feelers), and a pedicel, a narrow waistlike indentation between the thorax and abdomen. The crop, an organ located in the abdomen, is used to store food, which can later be regurgitated to feed other members of the colony.

Most ants are smooth-bodied, although some have spiny projections. Ants have strong jaws called mandibles, which are adapted for killing, crushing, chewing, cutting, or tearing, depending on the species and what it eats. Some species of ants have glands that produce formic acid, a strong acid that can be squirted on enemies, causing a burn or sting. Many ants have stingers that contain poison, and some, such as the harvester ants and fire ants, can inflict painful and, occasionally, fatal stings on humans and other animals.

Why Do Ants Have Tiny Waists?

Ants have tiny waists so they can wriggle their end parts freely! An ant’s waist has one or two movable parts. These parts allow the ant to twist and turn in different ways—an important feature for moving about an ant colony.

Ants have three main body parts: the head, the trunk, and the metasoma (meht uh SOH muh). The ant’s eyes, antennae, and mandibles (MAN duh buhlz) are located on its head.

Attached to the trunk are six legs with segments. Each leg has two claws at the foot. The claws hook into dirt, tree bark, or leaves, so ants can quickly walk, climb, and dig! Ants are strong, too. Many ants can lift 50 times their body weight!

The metasoma has two parts. They are the waist and the gaster. Organs for digesting, getting rid of waste, and reproducing are in the gaster. Some ant species have a sting at the end of the gaster to defend against other insects.

Where Do Ants Live?

There are about 10,000 species of ants. So it is not surprising that ants, like millions of other social insects, live everywhere on land, except where it is really cold. In fact, areas with warm and moist climates have the most types of ants and other insects.

Tropical rain forests are very rich in insect life. If all the animals in the Amazon rain forest were weighed, many scientists think ants and termites would make up one-third of that weight.

Ants are successful survivors. They have different ways of life that allow them to live in different habitats. And their small size makes it easy for them to find food and shelter.

Senses

The ant's most highly developed sense is that of smell. Ants have abdominal glands that secrete a variety of pheromones, chemical substances that cause specific reactions by other individuals. Pheromones act as alarms, sex attractants, and trail markers; and they help individuals recognize each other. Ants have a well-developed sense of taste, and can distinguish sour, sweet, bitter, and salty tastes. Their sense of touch is keen. Touch, or tactile, receptors are located on the feet and on hairs on the legs. The antennae are used for smelling, tasting, and touching.

Some species of ants have compound eyes and well-developed vision, while others have simple eyes that can only distinguish between light and dark. Some species of ants are blind.

Habits

Homes

Ants typically make their nests in or on the ground. The soil excavated to make the nest may be piled up around the opening to the nest, forming a mound or crater. The nest is typically composed of several long tunnels that lead to chambers. The chambers serve as storage areas for food and as nurseries for the young.

Some ants live in the wood of trees or rotten logs. The workers of one tree-dwelling species make nests by weaving leaves together with silky threads secreted by their larvae. Some ants have well-defined territories and build permanent nests. Others move from one site to another, building a new nest each time. Some ants share their nests with ants of a different species and sometimes with other kinds of insects, or with spiders. A number of ants make their nests in human dwellings, particularly in wood siding or in the foundation.

Food

Some species of ants eat live insects while others feed only on decaying animal matter. Others cultivate and eat fungi. Some ants gather seeds and grain for food. Several ant species tend "herds" of aphids and scale insects to obtain the sugary liquid, called honeydew, that they excrete.

What Else Do Ants Eat?

Ants eat fruit, flowers, and seeds, while others eat everything in their path, including small animals.

Ants have special mouthparts for grabbing and eating food. First come the mandibles, which are jaws that move from side to side. Ants use their mandibles to hold food, carry their young, and fight enemies. Behind the mandibles are the maxillae (mak SIHL ee), which are used for chewing. But ants do not swallow the food right away. First the food passes to a pouch behind the mouth. There, the liquid is squeezed out of the food. Ants swallow the liquid and spit out the leftover food pellet.

Ants have two kinds of stomachs—a stomach and a crop. Food an ant eats for itself goes to the stomach. Food it shares with others is stored in the crop. The ant spits up this food to feed other ants and larvae. Hungry ants may stroke each other or tap antennae to ask for food.

The Ant Colony

Ants are social insects, living in large colonies. The colony is typically divided into the following castes, or classes: queens (reproductive females), males, and workers (nonreproductive females). Although there are great variations in social structure among ant colonies, certain basic features are common to most species. These features are described in the following section.

What is a Social Insect?

Ants, termites, many bees, and some wasps have a real family life. They live in communities, and the members of a community depend on one another.

There are more than a million different species, or kinds, of insects in the world. Insects include beetles, crickets, butterflies, and houseflies. Insects come in many different shapes, sizes, and colors. But there are some things that all insects have in common. They all have six legs and bodies that are divided into three main parts. They all have tough, shell-like body coverings. And most, but not all, have wings.

Ants, termites, bees, and wasps may look a lot like these other insects. But as social insects, they lead very different lives.

Why Are Ants Social Insects?

Ants are social insects because they live and work together in communities. Here, they feed and protect one another. They raise and care for their young. This way of life is very different from that of solitary insects that spend most, and sometimes all, of their lives alone.

An ant community is called a colony (KAHL uh nee). Life in an ant colony is very organized. Each member has a job to do, from laying eggs to gathering food to fighting.

For most ants, colony life centers around the nest. The nest may be underground, in a mound, or even among the treetops. When ants build a nest, the dirt that piles up around the entrance forms an anthill.An ant colony is a very busy place. It can also be very crowded. There may be hundreds, thousands, or even millions of ants in a single colony.

Social Castes

Some colonies have one queen; other colonies have several. The queens are fed and otherwise tended by the workers. The males' only function is to mate with the queens.

The workers carry out such tasks as enlarging and protecting the nest, tending queens and young, and foraging. There may be only one kind of worker, or there may be several kinds, with body structures specialized for different types of work. The activity of workers is coordinated mostly through pheromones and body contact.

Depending on the species, queens live about 5 to 30 years, making them the longest-lived insects. Workers live about 1 to 3 years. Males live only for a mating season.

AntsAnts have complex social organization and specialized castes.
Who’s Who in an Ant Colony?

Like most social insects, ants have three castes, or classes. There are queen ants, worker ants, and male ants.A queen does not rule the colony, but she is an important member. She has one job—to lay eggs. Without her, a colony would die out. The reason is that only the queens in most species of ants can reproduce. They also live the longest—10 to 20 years. A colony may have one or more queens. A European wood ant mound, for example, may have hundreds of queens.

Worker ants may be the smallest, but they do the most work. All the workers are females. They care for the queen and her young. Worker ants build and repair the nest. They search for food and fight off enemies. Worker ants usually live one to five years.

Most male ants live only a few weeks or months. They do not work, and they die shortly after mating with young queens.

What Does an Ant Nest Look Like?

Most ant species build underground nests. Worker ants dig tunnels and chambers, or rooms, in the soil. As the colony grows, workers add more tunnels and chambers to the nest.

Ant colonies can grow to be quite large. Some tropical ants build downward to make more room. Their nests may reach 20 feet (6 meters) below the ground. Others, such as European wood ants, build upward. They build huge mound nests that may be 5 feet (1.5 meters) tall. Then the ants connect the mounds with scent trails. The group of nests may cover an area as large as a tennis court. Millions of ants may live in these nests.

The chambers in an ant nest have many different uses. The queen has her own chamber for laying eggs. Some chambers are nurseries for the growing young. Food is stored in other chambers. Still other chambers are resting places for hard-working ants!

Starting A Colony

Usually once a year, a colony produces a generation of queens and males. Queens develop from larvae fed a highly nutritious substance secreted by workers. Males develop from unfertilized eggs.

The queens and males are winged; they leave the nest in a series of large swarms, known as nuptial flights. Each swarm consists of either all queens or all males. The ants fly to other areas to mate with ants from other colonies. The males die after the flight. The queens drop to the ground, shed their wings, and look for a place to lay their eggs. After a single mating, a queen can lay fertilized eggs for several years. Unfertilized eggs are usually laid sometime in the spring or summer. The eggs develop into larvae, the larvae into pupae, and the pupae into adults---a process called complete metamorphosis.

The queen tends her first brood of offspring during their larval and pupal stages. This generation consists only of workers, who then take over the duties of tending the queen and her subsequent broods.

How Does a Queen Ant Start a Colony?

Most species of ants start a new colony in the same way. A queen ant is born in one colony, but she usually leaves that colony to start a new one. As young queens grow, they develop wings. A few weeks after becoming adults, young queens fly out of the nest to mate with winged males. The queens then shed their wings and look for nesting places.

When a young queen finds a nesting spot, she builds a chamber and seals herself inside. Then she begins to lay eggs. The queen cares for the eggs, which develop into larvae (lahr vee) and then pupae (PYOO pee). The queen feeds the young with her saliva. She does not eat during this time. Her body absorbs the unneeded wing muscles as food.

The eggs develop into small, female worker ants. Some of these workers leave the nest to find food for the colony. Others build onto the nest. The queen lays more eggs. Most develop into female workers. Others develop into males and young queens.

What Do Worker Ants Do?

Worker ants work¾and they work hard. All workers are females. But they very rarely become queens or reproduce. Instead, they care for the queen, the young ants, and the nest. Without its workers, an ant colony could not survive.

Worker ants may have one job or several jobs. They may keep the same job all their lives or change jobs from time to time. Some workers gather food for the colony. They store the food they harvest in special chambers in the nest. Other workers feed and care for the queen and her developing young. Still others build the chambers and tunnels. They use their saliva to make the dirt walls hard.

Some worker ants are soldiers. They defend the colony. In many species, soldier ants are larger than the other workers. The soldiers fight off enemy ants or insects. They may also use their large heads to block the entrances to the nest.

Who Is Minding the Eggs?

Ants go through four different stages, or steps, of growth. These stages are egg, larva, pupa, and adult. Worker ants care for the young ants through each stage.

After a queen ant lays her eggs, worker ants take them to hatching chambers. There, the workers care for the eggs and often groom them by licking. The eggs hatch in a few days to become larvae. During the larvae stage, the young ants look like tiny white worms.

Worker ants move the larvae to new chambers and feed them for a few weeks until they become pupae. In some species, the larvae spin cocoons before they become pupae. In other species, the pupae are covered only by thin, see-through skin. Pupae do not eat or move. But they do change. In two to three weeks, adult ants come out of the cocoons or skin. They are now ready to go to work!

How Do Ants Recognize Each Other?

Ants in a colony have a special odor that helps them recognize one another. Outsiders or enemies have different odors. Soldier ants smell these invaders and kill them.

Ants do not have ears. They “hear” vibrations through their sense organs. An ant’s antennae are its most important sense organ. Ants use their antennae to smell, touch, taste, and hear. It’s easy to see why an ant’s antennae are always moving. Antennae help ants find and taste food. They help ants recognize and touch one another. Antennae even help ants find their way.

Most ants have two compound eyes. A compound eye has many lenses. (A human eye has only one lens.) Because of their compound lenses, ants see things broken up, like an image in a kaleidoscope. Ants see movement better than shape.

Kinds of Ants

There are about 10,000 species of ants. Many species are familiar to humans, although many others are seldom seen, living almost entirely underground, or foraging only at night. Among the interesting or unusual ants are the following:

Carpenter Ants

build nests and tunnels in dead wood, trees, utility poles, and timbers of buildings. Although they do not eat the wood, carpenter ants can do considerable damage to it. Carpenter ants are found in temperate regions throughout the world. The workers are among the largest known ants. The black carpenter ant is the largest ant found in the United States. The workers are about half an inch (1.3 cm) long, and the queens about one inch (2.5 cm). This ant sometimes enters houses in search of sweet foods.

Driver, or Army, Ants

move their entire colonies every two to four weeks. They are found mainly in Africa and tropical America. Several species are found in the southern and southwestern United States, where they are called legionary ants. Driver ants are predatory, and their foraging parties are noted for ridding large areas of insects, lizards, and other small animals. Their sting is very poisonous, and they have been known to kill chickens and some larger animals. Driver ants have several kinds of workers, including soldiers. The soldiers are larger than other workers and have strong, hooked jaws.

Army antsArmy ants gang up to eat insects, lizards, and small animals.

Driver ants are nomadic; their movements are related to the hatching and growth of successive broods. While eggs are being laid and are hatching into larvae, the colony stays in one place. During this time, a previous generation hatches from pupae into adults. The entire colony then moves on to the next site through a leaf-covered tunnel built by the workers. The larvae are carried to the new site in the mouths of some of the workers.

Which Ants Are on the Move?

Army ants—thousands to millions of them—are almost always on the move. They do not build permanent nests. They just march along, carrying their young and looking for food. They kill and eat anything in their path. This usually includes spiders and other insects. But in some cases, army ants prey on larger animals that cannot get away quickly.

Each night, army ants stop to rest. They gather together to form a cluster on a tree branch or in a log. The queen and the developing ants rest deep within the cluster, where they will be safe.

When the queen is laying eggs, the army ants cluster in the same spot each night. They remain at this temporary campsite until all the eggs have developed into active larvae. When the larvae begin to grow, the cluster moves to a new spot each evening.

Fire Ants

are native to South America but are now also found in the southern United States. They eat a variety of foods, including fruit, vegetables, and insects. Fire ants are named for their painful sting, which produces a burning sensation. Armies of fire ants have been known to kill livestock. They are agricultural pests because they destroy young crop plants. Fire ants cover their nests with mounds of hard soil, some reaching a height of two feet (60 cm). They enter and exit the nest through several tunnels excavated in the mound.

Fungus-growing Ants,

found only in the New World, cultivate a certain species of fungus for their food. Some species of fungus-growing ants cut off leaves from trees and other plants and carry them to their nests. They chew the leaves into a pulp and use it as a base on which to grow the fungus. These ants are commonly called leaf-cutting ants. They are also called parasol ants because they hold the leaves over their heads when carrying them. Some fungus-growing ants construct their gardens from insect droppings.

Leaf-cutting antsLeaf-cutting ants cultivate fungus for food.
Which Ants Farm Fungus?

Leaf-cutter ants are farmers that grow their own food in underground gardens. The food they grow is a fungus, a kind of mold or mildew. The ants fertilize their fungus gardens with bits of leaves.

Leaf-cutters build huge colonies. Their nests can have a thousand chambers and tunnel down 20 feet (6 meters). Inside, up to a million ants may be at work.

Big and little ants are needed to farm the fungus. Large worker ants set out at night to gather leaves. They use their long, hooked mandibles to cut the leaves. Then they march back to the nest, holding the leaves high. For this reason, leaf-cutters are often called umbrella or parasol ants.

Inside the nest, smaller workers chew the leaves into a pulp, or paste. They put this paste on the fungus. Later, tiny ants harvest the fungus to feed the colony.

Harvester Ants

gather and store certain wild grass seeds, or cultivated grain. They gather the seeds from the plants and pick up those that have fallen to the ground. They store the seeds in underground chambers, and bring them up on sunny days and spread them out to dry. There are several species of harvester ants, found in temperate and subtropical regions. They can inflict very painful bites and stings.

Honey Ants

use certain workers, called repletes, as living vessels in which to store food. They collect nectar from plants or honeydew exuded by other nectar-eating insects and feed it to these workers. The repletes are gorged until their abdomens are many times normal size and they cannot move about. They hang from the ceilings of nest chambers and dispense the food, by regurgitating it, to the other ants during dry seasons when other food and water are scarce. There are a number of species of honey ants. They are found in the southwestern United States, Mexico, Australia, New Guinea, and parts of Africa.

Which Ants Herd Aphids?

Dairying ants “herd” aphids (AY fihdz)—just as people herd cattle! The ants keep the aphids together and protect them from other insects. Why do the ants do this? It’s because aphids produce something that the ants really like—honeydew. Aphids are small insects that suck plant juices and give off the excess as honeydew. Dairying ants eat the honeydew. They use their antennae to stroke the aphids, causing them to produce more of the sweet, sugary liquid.

Dairying ants take good care of their aphids. They will move their herd if the aphids need better plants to eat. They even store aphid eggs in their nests through the winter to start a new herd in the spring. A young queen may also take along an egg-laying aphid when she starts a new colony. This queen carries the aphid in her mandibles.

Black Ants

Little black ants are native to the United States and are found throughout most parts of the country. They are found in houses, in the cracks in sidewalks, and on lawns. Little black ants are attracted to human foods, particularly cooked meats and vegetables, and those containing sugar. They are active day and night, and are often seen carrying food back to their nests.

Slave-holding Ants

raid the nests of other ant species for larvae and pupae, which become slave workers in their colony after growing to adulthood. Some species of slave-holding ants are called amazon ants. Some slave-holding ants can live without slaves, if necessary. Other species are completely dependent, being unable to carry on the tasks of their colony alone. Slave-holding ants are widely distributed throughout the world.

What Other Ways of Life Do Ants Have?

Ants have many different ways of life. Harvester ants gather seeds and store them in special chambers. When harvesters need food, they chew the seeds to make a pulp called ant bread. They squeeze the liquid out of this bread and swallow it for food.

Honey ants store their food, honeydew, in special workers. The workers store so much honeydew in their gasters that they cannot walk. They hang from the nest ceiling and spit up honeydew when other ants tap them.

Slave-maker ants steal pupae from other ants and raise them as their own. When the pupae develop, they work for the colony, digging tunnels and feeding the slave-makers.

Weaver ants build nests from leaves. To do this, some workers hold the sides of a leaf together. Others take silk-spinning larvae and pass them over the edges of the leaf to “weave” the edges together.

Are Social Insects in Danger?

For the most part, social insects are not in danger. Their numbers are in the millions. And they reproduce at such a fast rate that they are not in danger of extinction. But these insects do face some dangers.

People often use strong chemicals to control insect pests. These pesticides can be dangerous to other insects, animals, plants, and the soil. They destroy both harmful and helpful insects.

Changes in the environment affect insects, just as they do all living things. But there are millions and millions of social insects. They will be creeping, crawling, and flying for a long time to come.

Ants make up the family Formicidae of the insect order Hymenoptera, which also includes bees and wasps. An example of a genus of carpenter ants is Camponotus; of driver ants, Eciton; of fire ants, Solenopsis; of fungus-growing ants, Atta; of harvester ants, Pogonomyrmex; of honey ants, Myrmecocystus; of slaveholding ants, Polyergus. The little black ant is Monomorium minimum.