Imported fire ants build unsightly mounds that interfere with farm operations.

In areas where fire ant populations are very high, the ants may reduce populations of other ground-dwelling insects, including native ant species, with which they compete. They also may attack the nestlings of ground-nesting birds and perhaps other wildlife, although impacts on wildlife populations are poorly documented. Fire ants have even been known to climb trees and enter bird nests. For more information about imported fire ants in wildlife areas, see FAPFS-006 Managing Red Imported Fire Ants in Wildlife Areas.

A secondary effect of fire ants is the misuse or overuse of insecticides applied in an attempt to reduce their populations. This can lead to surface runoff water contamination. See FAPFS-042 Estimated Amounts of Insecticide Ingredients Used for Imported Fire Ant Control Using Various Treatment Approaches.

For extensive analysis of the economic impact of imported fire ants in Texas and elsewhere in the United States, see information available on Fire Ant Economics maintained by Dr. Curtis F. Lard.

Imported fire ants (Solenopsis invicta and Solenopsis richteri) are invasive species that cause $6 billion in annual losses in the United States ( See Area Wide Fire Ant Suppression). Imported fire ants inflict painful stings and can kill human beings. There are large social and medical costs associated with this pest. The large mounds they build dot the landscape (average of 60 mounds per acre from Louisiana eastward, and 300 mounds per acre in Texas). The mounds are unsightly and can damage mowers and combines. Fire ants invade electrical equipment, causing short circuits and equipment failures. They cause ongoing expense to turfgrass managers. Currently, a USDA APHIS quarantine covers 320,000,000 acres in 14 U.S. states or territories.

Many aspects of imported fire ants can be beneficial, but they can cause many problems. In urban areas, imported fire ants cause problems because of their unsightly nests or mounds often found in open, sunny areas. The ants have an affinity for electrical equipment and can cause failures when they interfere with switching mechanisms, chew on insulation, and fill utility boxes with soil for nesting.

In agriculture, their tall, hardened mounds can interfere with field working machinery. Although fire ants eat certain insects, they protect and encourage population growth among sucking insects such as aphids, scales, mealybugs, and others that produce the sugary liquid called honeydew. The ants feed on the honeydew rather than eat the insects that produce it. Thus, they can increase the need for insecticide use for these pests in certain crops such as cotton and ornamental crop nurseries.