ifficult, even for experts. Identification usually requires 40 or more randomly collected worker ants for study.
Black Imported Fire Ant. The black imported fire ant, Solenopsis richteri, is very similar to the red imported fire ant. Its current distribution is limited to a small area of northern Mississippi and Alabama. It may be displaced from established habitats by the red fire ant. Scientists have long thought that the black and red fire ants were 2 distinct species. Recently it has been discovered that hybrids of these ants produce viable offspring, and some scientists now wonder whether they are simply 2 races of the same species, varying in color and perhaps behavior.
Southern Fire Ant. The southern fire ant, Solenopsis xyloni, is a native species that occurs from North Carolina south to northern Florida, along the Gulf Coast and west to California. In California it occurs in the lower altitudes from Southern California up through Sacramento but is seldom found along the coast in central to northern California. This is probably our most common native species of ant but its distribution is greatly retarded when the Argentine ant is present. However in areas where the Argentine ant is controlled, populations of this species rapidly return.
Colonies may be observed as mounds or more commonly may be constructed under the cover of stones, boards, and other objects or at the base of plants. These ants also nest in wood or the masonry of houses, especially around heat sources such as fireplaces. Nests often consist of loose soil with many craters scattered over 2 to 4 square feet. In dry areas nests may be along streams, arroyos, and other shaded locations where soil moisture is high. Southern fire ants usually swarm in late spring or summer.
The workers are very sensitive to vibrations or jarring. If their nest is stepped on they will rush out and sting the feet and legs of the intruder. Individual reaction to their venom is quite variable depending on allergic reaction. There is a least one case of a human inf