Since the 1870’s members of the Pseudomyrmex ferrugineus group and the interactions with their acacia tree hosts have been intensively studied. P. ferrugineus was first described in 1877 by Frederick Smith. He collected his original specimens the in Mexico and named the species Pseudomyrma ferruginea. Because of Daniel Janzen’s research in the 1960’s, Pseudomyrmex ferrugineus is one of the most well studied acacia-ants.
These ants occur in eastern and southern Mexico south to El Salvador and Honduras (Ward, 1993) and are mutualistic with several species of Mesoamerican acacia trees. In this relationship the acacia trees provide shelter and food to the ants in return for protection from herbivores, fungi, and other plants. These ants patrol their host acacias 24 hours per day and quickly respond to intruders. P. ferrugineus is more aggressive than other Pseudomyrmex ants due to their protective nature (Janzen, 1966).