What is the basic biology of the fire ant?

Imported Fire Ants April 25, 2012 Print Friendly and PDF

Colonies of fire ants are established by mated queens after a mating flight. Mating occurs in the air, after which mated queens land, lose their wings, and seek a place to hide. 

The queen digs shallow depressions and lays eggs from which worker larvae (sterile females) hatch and develop. During this time, the queen survives on the nutrients from her deteriorating wing muscles. Once the first worker ants develop to adults, they care for the queen, her egg production increases, and the colony begins. 

Colonies will survive as long as one queen and a few workers are present. Killing the queen or preventing her from laying eggs will eventually kill the colony. 

There are both single queen (monogyne) colonies and multiple queen (polygyne) colonies. The single queen colony has only one queen per mound, and workers range in size from about 1/8 to 1/4 inch long. Workers from single queen colonies will kill any fire ants they encounter from other colonies, including newly mated queens.

The multiple queen colony usually has more than one and up to hundreds of queens per colony. A majority of the worker ants are the same size with only a few large workers. Multiple queen colonies are less territorial. They are less aggressive toward fire ants from other colonies and may adopt newly mated queens that are genetically compatible.

Fire ants live in the soil in an extensive network of tunnels. How deep this network extends into the ground depends on the age and size of the colony, soil texture, and depth of the water table. Tunnels in fire ant nests have been found to a depth of 10 feet or more.

Temperatures that dip below 10 degrees F over at least a couple of weeks could significantly affect fire ant populations. Ultimately, cold winter temperatures limit how far north fire ants can spread. Fire ants don't truly hibernate, but they are less active in cold weather.

Fire ants spread through natural and artificial means:


  • Newly mated queens fly or are blown into new areas.
  • Rafts or balls of flooded colonies float to new areas.
  • New colonies “bud off,” which is how fire ant colonies with multiple queens start new colonies.


  • Mated queens or colonies are transported via infested sod, hay, beehives, or nursery stock.
  • Newly mated queens are transported on vehicles where they have landed.


Fire ants eat almost anything containing oils, proteins, or sugars. Insects are a common food source. Workers sting other insects and tear them into manageable pieces, which they take back into the colony. Fire ants have been shown to decrease some pest insect numbers.

Although fire ant workers can chew solids, they can swallow only liquids. Solid foods that are brought back into the colony are digested into liquid form by larvae in the fourth stage of development and fed to other members of the colony.


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