Identification. Like other Hymenoptera, females of dangerous ant species have a stinger at the posterior tip of the abdomen. Their constricted “waist” between the thorax and posterior abdomen and their elbowed antennae distinguish them from similar insects. The dangerous United States species belong to genera _Solenopsis_ (fire ants) or _Pogonomyrmex_ (harvester ants). The easiest way to distinguish these ants is by their mounds. Fire ants build elevated earthen mounds 8-90 cm (3-36 in) high, leaving the surrounding vegetation relatively undisturbed. In contrast, harvester ant mounds are usually flat or slightly elevated and are surrounded by a defoliated area 0.6-3 m (2-10 ft) or more in diameter. Also, harvester ants are 2 to 3 times larger than fire ants. Distribution. The Florida harvester ant, _P. badius_, distributed throughout the Southeastern States, is the only harvester ant known to occur east of the Mississippi River. West of the Mississippi, the red harvester ant (_P. barbatus_), the California harvester ant (_P. californicus_), and the western harvester ant (_P. occidentalis_) are found in different individualized distribution areas. The two most important fire ant species were introduced into the United States from South America. The red imported fire ant (_S. invicta_) was introduced about 1940 and is well established in the Southeastern States. Currently, this ant infests Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North and South Carolina, and Texas. The black imported fire ant (_S. richteri_) was introduced about 1918; its distribution is limited to an area in northeastern Mississippi and northwestern Alabama. Two less important native species, _S. geminata_ (tropical or native fire ant) and _S. xyloni_ (southern fire ant), occur in localized areas of a few southern states. Biology/Behavior. Ants of the _Solenopsis_ and _Pogonomyrmex_ genera are diurnal soil-inhabiting insects that prefer to nest in open areas. These ants are social insects; their colonies consist of at least one reproductive queen, several males, and many nonreproductive female workers. Fire and harvester ants are particularly dangerous because workers defending their nest can inflict repeated stings, and multiple human envenomizations may occur when a victim comes in contact with a mound. Avoidance/Control. Familiarization with the appearance of the ant mounds is necessary in order to avoid them and prevent accidental envenomizations. Since small children are often the victims of multiple stings, parents should insure that the mounds of dangerous ant species are not present in play areas. This is particularly important where the red imported fire ant occurs. Mound treatments with mirex have been effective in controlling _Solenopsis_ and _Pogonomyrmex_ ants. The Environmental Protection Agency limits the use of this insecticide, and it must be applied in strict accordance with EPA and product label instructions.