Ants1, 2

Ants fast facts

  • They have a narrow waist formed of 1 or 2 segments called the pedicel or peteole, see the drawing below.
  • Antennae are strongly elbowed.
  • All species live socially.
  • "Ants eggs" sold as fish food are actually ant pupae (usually of the wood ant Formica rufa), in their cocoons.
  • Earliest fossil remains are from 120 million years ago, and they are thought to have evolved around 140 MYA.
  • Ants were the first farmers. Fossil evidence shows they were farming fungus 80 million years ago, and feeding the fungus on insect faeces and dead insects.
  • Ants create and fertilise the soil by recycling nutrients.
  • Adults range in length from 0.25 mm - 4.0 mm.
  • The largest ant is the South American Dinoponera gigantea. It has quite small colonies, though, of around 40 individuals.
  • There are around 16,000 described species worldwide, and 60 species in the U. K. (this includes 10 alien species). it is believed that many more species await discovery.
  • A queen ant can live for as long as 15 years.
  • Adult males and queens have wings, but after the nuptial flight the queen removes her wings, and the males die.
  • In some species the queens and workers have stings, and in other species they can squirt formic acid from their rear end.
  • The largest ant colony is thought to stretch 6000 km along the coast of north west Italy, along the Mediterranean coasts of France and Spain and up the Atlantic coasts of Portugal to reach the north of Spain. It is the introduced Argentine ant species, Linepithema humile.
  • In the Amazon rainforest there can be more than 8,000,000 ants per hectare (Holldobler & Wilson, The Ants, 1990) One study found over 200 species in a single tree..
  • There are 1015 - 1016 ants alive in the world at any one time according to Holldobler and Wilson in the book Superorganism: The beauty, elegance and strangeness of insect societies (2009).
  • In some rain forests the biomass of ants can be 4 times the biomass of all vertebrates combined! And it is estimated that they form 15% of the total biomass of the planet.
  • Live ants - mainly carpenter and army ants - have been used in Africa, India and the countries around the Mediterranean to clean up wounds. The sharp jaws of the ant are placed so that they fasten the edges of the wound closed; the jaws lock and stay in place even when the rest of the ant's body is removed. Stitches without thread and needles!

Formica rufa, adlut worker wood ant

Ants farming aphids

ants farming aphids

The photograph above shows ants (Lasius niger) guarding aphids while the aphids suck sap from a rose bush. The aphids get too much sugar from the sap and excrete it (this liquid is called honeydew) and the ants lap it up; drinking some themselves, and taking the rest home for their nest mates and grubs. Ants were farmers millions of years before humans even existed.

The tip of every leaf was guarded by at least one ant, and other ants patrolled over the aphids, and up and down the stems. Any other insect, or even a camera strap would be nipped and squirted with formic acid. So the aphids are free to suck in peace and the ant gets a sugary reward. And the rose bush? Well it was quite a big bush and a short time later it had many fragrant blooms.

Ant life cycle

In temperate regions there is little visible ant activity during the winter. As the temperature rises sexuals - males and queens - are produced, and these have wings. Sexuals from different nests are released at the same time. The conditions at the time of release are usually warm, humid with still air and moist soil. This synchronous release from different nests prevents inbreeding. These mass flights of sexuals provide a good meal for birds, spiders and many other predators.

Lasius niger sexuals exiting nest, winged ants leaving nest

The photograph above shows Lasuis niger sexuals emerging on a sunny day in Greyfriars Kirkyard, Edinburgh. The males and queens fly off and mate. This is the only time the queen will mate, and the sperm she receives in this mating must last her a lifetime of egg laying, which may be more than 10 years.

After mating the queen lands and searches for a nest site. Before digging into damp soil she breaks off her wings. She will never need them again, and will probably never see daylight again.

She digs a small chamber in the soil and lays her first batch of eggs. The energy for this comes from the degeneration of her flight muscles. She tends her batch of white, sticky eggs, and when they hatch she feeds the larvae. During this time she doesn't eat or leave the chamber.

Ant pupae

Once her larvae have pupated and hatched out as sterile female workers they will take over all the nest duties, and forage for food, leaving the queen free to concentrate on her only duty now, which is egg laying. The first workers are usually smaller than normal size for the species.

This is the typical life cycle, but there are variations. In the more "primitive" species the queen may forage in the early stages of the nest. In other species colonies may bud off the main nest to become satellite colonies. Some species raid other nests for slave ants which they take before the slave has hatched into an adult.

The photograph above shows the pupae of Lasius niger. The grid is 5 mm. Ant pupae are often sold dried as fish food and called ants eggs.

The secret of ant success

  1. Division of labour. Whether it is farming (aphids, etc.), food processing (fungus), or predation, ants divide up the task to achieve their aims.
  2. Modification of their environment to better suit themselves and their livestock and food production. For example leaf cutter ants use antibiotics and symbiotic bacteria to protect their food crop of fungi. Weaver ants make their nests by stitching leaves together using their larvae to produce the silk thread.

Ant communication

Communication is mainly done by chemicals called pheromones. There are chemical trails to food sources, trails during exploration, and chemical alarm warnings.

The chemicals are produced in various glands, e. g. cloacal, Dufor's, poison, rectal, and tibial. Grooming and trophallaxis (liquid food exchange) also spread chemicals of recognition and queen condition throughout the colony.

The ant has made herself illustrious
Through constant industry industrious.
So what?
Would you be calm and placid
If you were full of formic acid?
Ogden Nash

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