Synonym(s): Dark Rover Ant
Adult Description: Brachymyrmex patagonicus is a small dark reddish-brown species with pale tarsi and mandibles and brownish-yellow antennae. The promesonotum usually has at least four erect hairs. The gaster has sparse, but rather long pubescense. The head is slightly wider than long. The eyes are relatively large; about as long as the length of the malar space. Minute ocelli are present, and the scape surpasses the occipital border.
Larva Description: Typical ant larvae.
Host Plant: N/A
Ecological Threat: It is unclear what affect, if any, this species will have on local native species. However, based on its abundance where established, the potential for negative impact exists. In southern Alabama and Mississippi, this species, along with several other introduced species are now the most commonly encountered ants. Rover ants are capable of rapid reproduction and spread. It is not known whether this will lead to permanently high population levels, or whether some form of biotic resistance will eventually control this species.
Biology: This species can be found nesting in rotting wood and soil. This ant can nest in a variety of habitats ranging from sand at the base of plants, soil in rich mixed forests, and hardwood mulch in suburban settings. The Rover Ant is considered a nuisance pest and is being found increasingly in houses and other man-made structures. Winged reproductives (Alates) have been collected from late April through early August.
A major reason for the success of B. patagonicus in the United States may be its ability to thrive in a variety of habitats, especially disturbed sites. Other contributing factors could be its ability to coexist with a variety of other dominant ant species, such as pyramid ants (Dorymyrmex bureni), the Imported Red Fire Ant (Solenopsis invicta), Pheidole moerens (no common name), and Pheidole obscurithorax (no common name). This is similar to other Brachymyrmex species, which also occur with other dominant ant species.
History: This species was first reported from the United States as Brachymyrmex musculus Forel from St. Tammany Parish, Louisiana in 1978 from a single colony collected in 1976 from sawdust beneath a recently cut live oak tree. Experts speculated that it could have been introduced into the United States through New Orleans, which is a reasonable entry point for tropical species, although other localities, such as Mobile Alabama, or Pensacola Florida, are just as likely.
U.S. Habitat: These ants are very opportunistic, are habitat generalists. They are known to enter houses, hospitals, schools, or other man-made structures to forage and/or nest. Occasionally these infestations may be quite large, with nests being found in the structure of the buildings, especially in bathrooms and kitchens, in light sockets and in electrical outlets, inside cinder blocks of exterior walls, and under shingles.
Native Origin: Argentina
U.S. Present: Currently, the Rover ant, Brachymyrmex patagonicus, has invaded much of the Southeastern United States including: Georgia, Florida, Alabama, Mississippi, Arkansas, Louisiana, and Texas.
The rover ant has been found in Smith County, in East Texas near the Louisiana border and as far west as College Station. However, due to the rapid spread, difficulty in identification, and minute size, the rover ant could be ensconced in many other Texas counties.
Due to the very small size and stereotypical ant color, the rover ant, Brachymyrmex patagonicus, can be easily confused for many other ant species. It is most often confused with the related species Brachymyrmex musculus. In fact early literature on the Rover ant misidentified them as this species. In addition, the little black ant, Monomorium minimum, is mistaken for the Rover ant.
Pest control operators (PCOs) in central Mississippi and Florida have reported difficulty in controlling this species even with repeated applications of pesticides. Pest control operators have also noted that although this species has been been found in various food sources, it seems to be especially attracted to sweet liquids.
MacGowan JA, JG Hill, and MA Deyrup. 2007. Brachymyrmex Patagonicus (Hymenoptera: Formicidae), and Emerging Pest Species in the Southeastern United States. Florida Entomologist 90(3) p. 457-464.