Antenna 12-segmented, without a club. Thorax lacks spines, profile unevenly rounded . Pedicel 1-segmented . Gaster with anal opening slitlike, lacking circlet of hairs . Stinger absent but can bite on provocation.
Workers emit a stale greasy or musty odor when crushed.
Colonies are located in moist situations near a food source. In the autumn, outside colonies join together to form huge overwintering nests. Winged female reproductives are rarely seen because mating takes place inside the nest. The workers are very aggressive and usually eliminate other ant species and some other insects from the area. However, ants from different Argentine ant colonies are friendly and do not fight.