Iridomyrmex humilis, or the Argentine ant, as the species is more commonly known, is an invasive ant pest that has become well established throughout Louisiana. As their common name makes clear, these ants are native to South America, and they were first documented in Louisiana during the late 19th century after colonies were recovered in New Orleans. Argentine ants have been transported into Louisiana numerous times on shipments of nursery stock arriving at the Port of New Orleans from South America. This ant species continues to spread to new areas by means of human transport, as colonies contain millions of workers and hundreds of queens that easily infest cars, boats and recreational vehicles.

Once these ants arrive in a new area, queens immediately begin reproducing while workers set about constructing new nesting sites. These ants are notable for their massive colony size and their habit of traveling long distances in clustered masses that pest control professionals are often powerless to stop. Because of this, area-wide pest control efforts are often necessary for halting this species further spread into new urban and suburban areas. However, there are plenty of things that homeowners can do to protect their homes from Argentine ant infestations.

Argentine ants forage on the ground and within trees, and they establish new colonies beneath rocks, bundles of plant matter, fallen branches, concrete slabs, landscaping ornaments, and mulch. Nomadic clusters of Argentine ants contain countless queens that continuously establish colonies while the larger mass continues to migrate to new territories. Because of this unique dispersal behavior, Argentine ant colonies are interconnected over their entire habitat, which can span several hundred square miles. Argentine ants often establish harborages in decayed wood, particularly wood siding that has become saturated with moisture. In order to prevent wood siding from becoming hospitable to Argentine ants, shrubbery should be regularly trimmed to prevent moisture from building up within siding and other sources of wood on the external walls of homes.

Has your neighborhood ever been invaded by Argentine ants?