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United States Department of Agriculture

Agricultural Research Service

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Natural Enemies
USDA Agricultural Research Services Web site on area wide suppression of fire ants.


Natural Enemies

Using natural enemies to provide biological control means no problems for people or pets.

A reasonable solution for fire ants is release of natural enemies to provide biological control. Natural enemies of fire ants have been found in South America and have proven safe and effective. Natural enemies spread on their own.

Two effective natural enemies of fire ants have been developed as biological control agents: Thelohania fire ant disease and decapitating flies.

Natural enemies can provide control wherever ants are. Most affect only fire ants, not other species. They also can improve and extend the effectiveness of insecticide treatments.

Biological Controls

Biological controls are organisms that kill fire ants in their native South American habitat. These have only recently been brought to the United States. The USDA-ARS has imported, isolated, and mass-produced these biological control organisms for release.

Decapitating Flies
Decapitating flies in the genus Pseudacteon attack fire ant workers and cause them to hide instead of feed. Female flies lay eggs that develop inside the fire ant's head, causing the head to fall off. Adult flies emerge from the severed head and attack other fire ants.

Decapitating fly life cycle:

  • Lay eggs on worker ants.
  • Larvae migrate to head and develop into adults.
  • Fire ant head falls off.
  • Adult flies emerge from severed head and attack other fire ants.

Decapitating fly behavior:

  • Female flies chase foraging fire ants back to colony.
  • Eggs are laid by flies on the thorax of ants.
  • Foraging is disrupted as fire ants try to hide.

Microscope photograph of the fire ant disease organisms. Fire Ant Disease
Fire ant disease, Thelohania solenopsae, is a protozoan disease that weakens the entire colony. Weakened colonies mean fewer fire ant reproductives to start new colonies. Fire ant disease is introduced into colonies by placing infected larvae in the mound.
Photograph of a decapitating fly. Photograph showing a decapitated fire ant.


Areawide Suppression of Fire Ants main menu

Last Modified: 10/24/2014
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