MARCH
2004

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

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Check out these books by Tom Turpin:

Flies in the face of fashion

What's Buggin You Now?

 

 

 

03-25-04

Download the audio of On Six Legs: MP3, WMV.

"The Ants Go Marching Two by Two, Hurrah, Hurrah"


Ants are very common insects. So common, that many scientists consider ants to be the most successful of all insects. In fact, if you just count number of individuals, ants outnumber most other terrestrial animals.

Ants live in colonies that vary greatly in size, from a few dozen to thousands of individuals. Ants are social insects, and colonies have at least three castes. These castes are queens, males and workers. The workers are sterile, wingless females and are the ants most people encounter, since they look for food outside of the nest.

Male and female ants have wings used for mating flights. The queen also uses her wings to fly to new nest locations. Once the queen establishes a new nest, she chews off her wings. They are of no value in a new home. The wing muscles are absorbed to provide energy for the queen to start laying eggs. In addition, the bulky wings just get in the way in the close confines of a nest. The queen, like a human bride, finds that her wedding dress is not functional attire for raising a family.

Ants exhibit a wide range of lifestyles. Some are carnivores. They feed on the flesh of other animals, either living or dead. Army ants exhibit such feeding behavior. These ants are mostly tropical. They are nomadic and travel in distinct armies. Like raiding armies on the move, no animal life is safe as they sweep across the countryside.

The carnivorous habit of ants includes feeding on other species of ants. This leads to furious battles between nests of ants. One battle was recorded by Henry David Thoreau in his story, "The Battle of the Ants." In this story, Thoreau chronicles a battle between a group of black ants and smaller red ants. He appropriately compares the fighting to legendary battles in Greek mythology.

Many species of ants feed on sap, nectar or honeydew. All of these substances are high in sugar and are prized by ants as a food. It is for this reason that some species of ants actually farm aphids. These ants collect honeydew produced by the aphids. Aphids are sometimes called ant's cows. The ants protect the aphids from predators and even move their "cows" to greener pastures when necessary. A few species of ants also store aphid eggs in their nests during the winter.

There are ants known as harvester ants. The name is based on the fact that these ants harvest seeds, which are stored in the nest as a food resource. Other ants actually produce food. These ants are known as leaf cutter ants. The ants harvest leaves and bring them into their nest. They do not feed on the leaves, though. The ants start growing fungus on the leaves in chambers known as fungus gardens. The fungus is consumed as food.

One interesting food storage habit of ants involves using living ants as storage tanks. These ants are known as honey ants. Some individual ants serve as reservoirs for the honeydew collected by other workers. These ants, known as repletes, hang from the roots of the nest chambers filled with honeydew. When other ants need honeydew, they stroke the mandibles of the replete, which prompts the living storage tank to regurgitate some of the sweet liquid.

A well-publicized habit of ants is that some species utilize other species of ants as slaves. A few species of ants are entirely dependent on slaves. The process varies some, but frequently involves a queen moving into another species of ant nest and killing the resident queen. The nest workers then adopt the new queen and take up the duty of rearing her offspring. These workers then make raids on other ant nests, where they kill the workers and bring back the pupae to rear as slaves.

So, when the ants go marching two by two, as the old children's song recounts, those ants are on a mission. It could be to harvest seeds, milk cows, battle with neighbors or even capture slaves. Who said insects sometimes behave like humans?

 

 

Writer: Tom Turpin
Editor: Olivia Maddox