When it comes to stinging ant pests in the United States, red-imported fire ants get all the attention, but as it happens, the country is home to a few native fire ant species. Solenopsis xyloni, or the “southern fire ant,” is the most abundant fire ant species in the US, and their habitat range spans the southernmost states from California to the Carolinas. Although the southern fire ant inflicts painful and potentially dangerous stings to humans, their venom is not as potent as that of their imported relatives. That being said, southern fire ants are aggressive toward anything they perceive as a threat, and they will not hesitate to swarm and inflict repeated stings on humans. Multiple case reports have been published that describe medically significant, and even fatal, consequences of southern fire ant stings. In addition to being a potential medical threat, southern fire ants frequently establish nests within wall voids, cracks in brick and cement masonry, beneath flooring, and other dark enclosed areas within homes.

Before the red-imported fire ant was introduced into the US, southern fire ants were the primary ant pests of medical significance in the country. While indoor southern fire ant infestations are still common, infestation rates decreased substantially following the arrival of another invasive ant species, Argentine ants. Argentine ants, while not medically harmful, are tremendously problematic pests in urban and suburban areas due to the massive size of their highly mobile colonies. Not only due Argentine ants invade homes, but they also pose an ecological threat, as they displace populations of native ant species in every region where they become established.

Once Argentine ants became abundant in urban and suburban areas of Louisiana, southern fire ant infestations and envenomation incidents decreased. Due to successful area-wide pest management efforts, Argentine ants are now well controlled in urban and suburban areas of Louisiana. In fact, some control programs have resulted in the eradication of Argentine ant populations from certain areas, which is a rare feat. Unfortunately, in many populated areas, southern fire ants have emerged in large numbers in response to the removal of Argentine ants.

Have you ever encountered ant nesting mounds in your yard?