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ants, fourmis

Formicidae

What do they look like?

Ants are skinny insects. Like their relatives the wasps, they have a narrow connection between their abdomen and thorax. They have chewing mouthparts, and their antennae are bent in the middle. Some ant species are very tiny (1-2mm long), but some tropical species are very large (30 mm). Most species are 5-15 mm long. Some ant species can sting, and all can bite. Ants have lots of glands for producing chemicals. Most ant species are brown, but some are black, some are yellowish, and some are partly or entirely red.

Each ant colony has several different kinds of ants. They are all the same species, but they look different. Most of the ants you see are workers. They are female, but they cannot reproduce. They do all the work in the nest and protect it from enemies. Some ant species have different sizes of workers for different jobs: large ones with big jaws hunt or protect the nest, while smaller ones work inside, tending the young and digging. Inside the nest is the queen, she is a large female, and is the only one who can lay eggs. Some ant species have several queens in a nest, some have only one. At certain times in the summer there will be new queens and males in the nest as well. They have wings, and fly out to mate and start new nests. Males are usually smaller than females. Only males and queen ants have wings, but the queens remove their wings when they start a new nest. Worker ants never have wings.

  • Sexual Dimorphism
  • female larger

Where do they live?

Ants are very important insects all around the world, especially in tropical regions. There are over 11,000 species in the world, and at least 90 species in Michigan.

What kind of habitat do they need?

Ants are found just about every habitat on land except the very coldest. All ant species need sheltered places to nest and take care of their offspring. Most species nest underground, but some nest in trees. Some very small ant species can make nests inside acorns and other small hiding places.

Adult ants can live in drier conditions than many other invertebrates, but ant eggs and young need humid conditions to survive.

How do they grow?

Ants have complete metamorphosis. Queen ants lay eggs. The baby ant that hatches from the egg is a larva, with no legs, just a soft white body like a worm and a small head. The larvae are fed by the queen (in the first generation) and then by workers. The amount and kind of food an ant larva gets helps determine how big it will be as an adult, and whether it will be a worker or a queen. Each larva grows and molts, and eventually spins a small cocoon of silk, and inside the cocoon it transforms into a pupa. The pupa is a resting stage, it doesn't move or eat, but just completes the transformation into an adult ant. The new adult emerges from cocoon to join start working for the nest.

How do they reproduce?

Ants live in colonies where one or a few females, called queens, lay all the eggs. Most of the queens' offspring become worker ants that do not reproduce. A few are males, and some become new queens. Each queen ant can lay thousands of eggs per year.

  • How often does reproduction occur?
    In most species, queen ants only mate once in their life.
  • Breeding season
    Summer

When a new queen finds a good place for a nest, she builds a small chamber and lays some eggs. When the eggs hatch, she finds food, and feeds and takes care of them until they mature. They become workers, and they take over all the work in the nest. The queen does nothing but lay eggs.

How long do they live?

Queen ants can live for several years. Workers may live for a year but many only live for a few months. Males die as soon as they mate, so they only live for a few weeks. Sometimes a nest has several queens, and they can keep a large colony going for many years.

How do they behave?

Different ant species are active at outside the nest at different times of day. Many are active at night, some in the daylight. Workers are active inside the nest as long as it is warm enough: tending the young, expanding the nest, collecting food, disposing of waste, and protecting the nest from predators and parasites. Ants often carry food and water by swallowing it, and keeping it in a separate stomach, then regurgitating it to share with other nestmates. Ants use chemicals to work together. If their nest is attacked they produce alarm chemicals that cause other workers to come and help defend the nest.

How do they communicate with each other?

Ants can see, but not very well. They mainly communicate with scent and touch. They have complicated chemical signals that allow them to work together on different tasks. They often spread information by touching each other's antennae or head. Some ants also make noises by rubbing their legs against their body.

What do they eat?

Ant species eat many different foods. Some specialize in sugary liquids like nectar and the "honeydew" produced by aphids and other insects (see Aphids). Many eat other insects and other small animals, and scavenge dead meat. Some others specialize in eating seeds or fungus. Ants drink from dew, rain drops, and puddles, and sometimes they get their moisture from their food (like nectar).

Many ant species store food in their nests, especially the seed-eating ants. Others eat fungus that they grow in their nest. Ants that find a big food source leave a chemical trail, so that their nestmates can find the food too. Pretty soon there is a busy column of ants going back and forth from the nest to the food source.

Leaf-cutter ants live in warm climates, they cut up leaves and carry them into their nests underground. They eat the fungus that grows on the leaves. Army ants and driver ants roam through jungles and tropical habitats eating any animals they can find. They are big ants with sharp jaws, and there are many thousands of them in a group. They will eat any animals, even large ones, that they can catch.

What eats them and how do they avoid being eaten?

Worker ants attack predators, they will die to protect their nest. Some ant species can sting, and all can bite (though the little ones can't hurt a large animal). Many ants also have toxic chemicals they can spray on their enemies.

What roles do they have in the ecosystem?

Ants are very important in lots of roles. Some species disperse seeds, some are important predators of insects, some tropical species are important herbivores. Their digging often improves the soil for plant growth.

Species (or larger taxonomic groups) that are mutualists with this species
  • Aphids
  • Some caterpillars

Do they cause problems?

Ants can be major pests. Carpenter ants make their nests in wood, including houses, and several ant species come into houses looking for food. In the tropics leaf-cutter ants attack crops in the fields. Some stinging ants can be dangerous to people. Recently an ant species from South America was accidentally brought to the southern United States. It is called the Imported Fire Ant, and it makes large nests with thousands of stinging defenders.

  • Ways that these animals might be a problem for humans
  • injures humans
    • bites or stings
  • crop pest
  • household pest

How do they interact with us?

Ants are important predators of insects, including flies, caterpillars, and other pests.

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

Several ant species are considered threatened or in danger of extinction. This is because they live in special habitats that are very rare and may be destroyed by human construction or environmental change.

  • IUCN Red List [Link]
    Not Evaluated

Some more information...

In some parts of the world, including the United States, ant species have been accidentally brought in from other continents. These invader ants are causing a lot of problems.

 
University of Michigan Museum of ZoologyNational Science Foundation

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. "Formicidae" (On-line), Animal Diversity Web. Accessed December 18, 2014 at http://www.biokids.umich.edu/accounts/Formicidae/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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