Black fire ants, Solenopsis richteri (Forel) were accidentally imported around 1918. Scientists think they were brought into the United States near Mobile, Alabama. The red imported fire ant, Solenopsis invicta (Buren), arrived during the 1930's. At first, scientists thought the two ants were variations of the same species.
As the red imported fire ant spread, it displaced the black fire ants. The red fire ants have spread across the entire country while the black fire ants are confined to a limited area. The black fire ants are found in eastern Mississippi, western Alabama, and southern Tennessee.
Black fire ants are ground-nesting ants. In their territory there can be hundreds of colonies per acre. These ants have been a serious urban and agricultural pest for many years. They cause millions of dollars of economic harm every year.
Black fire ants damage okra, eggplant, soybeans, and many other crops. They damage crops in several ways. The workers chew the bark and stems of the plants. They enter some fruits for the sugary liquid. The workers also gather oil from seeds to feed the immature ants.
The black fire ants cause damage to plants by protecting aphids and other plant-feeding insects. The aphids feed on plant juices that they get from the leaves. The aphids use the plant juices to produce honeydew that the ants eat.
Black fire ants also cause medical harm with their bites and stings. Some people have an allergic reaction when fire ants sting them. People who live in the areas where fire ants are common have learned to supervise children and pets closely when they are outdoors.
Scientists have found that the black imported fire ants are able to mate with the red imported fire ants. The hybrid offspring may be a more serious challenge then either of the two original species. Scientists think that the black imported fire ant along with the red imported fire ant and their hybrid have displaced two native fire ant species, the tropical fire ant and the southern fire ant.