Polygynous fire ant colonies reach higher densities than monogynous colonies and may be harder to control. Imported fire ants are primarily a people pest. Fire ants interfere with hay harvesting and maintenance of pastures and recreational turf areas. They present the greatest problem around dwellings where direct contact with humans is most frequent. Concern arises from multiple stings often experienced by young children.
Fire ants act as both pests and beneficials in crop systems.
In the role of pest, fire ants have a pronounced tendency to protect aphids from their predators, allowing aphid populations to explode unchecked. The costs incurred by this activity of ants are very difficult to quantify, but can probably be quite significant. In cotton, ant farming by fire ants actually appears to accelerate the destruction of aphid populations by a fungal pathogen. They become particularly abundant in reduced tillage systems where their mounds do not suffer frequent disturbances, and can become key components of these systems. It is difficult to calculate the positive economic impact of fire ants in row crops, but if a single insecticide application is saved over 1 million acres because of ant predation on pests, the benefits accrued to growers would be somewhere between 6 and 10 million dollars.