Linepithema humile, or the “Argentine ant,” as the species is more commonly known, is a South American ant species that has established an invasive habitat in the southern US states. Argentine ants were first discovered in the US back in 1891 when colonies were recovered in New Orleans, and today they are one of the most common indoor ant pests in Houston and other cities along the Gulf Coast. According to a recent nationwide survey of pest management professionals, Argentine ants were the fourth most commonly controlled ant pests in the country during the 2016 year.
An Argentine ant colony consists of an original “parent nest” surrounded by numerous secondary nests established by workers. During the spring and early summer months, queens and a small number of workers leave parent nests to establish new colonies, a process known as “budding.” Unlike most ant species, Argentine ants from separate colonies do not respond to one another’s presence with hostility. In fact, multiple Argentine ant colonies regularly integrate to form supercolonies. Infestations normally involve a massive number of workers entering homes from numerous outdoor nests located in lawn-soil, and these nests are typically associated with multiple colonies.
Argentine ants nest in moist soil beneath sidewalks, concrete slabs, and plants, against foundations, and within decayed wood, such as fallen tree branches and tree stumps. It is not uncommon for these ants to establish indoor nests within potted plants, beneath sinks, and near leaking pipes within wall voids. According to a study conducted by Stanford researchers, Argentine ants invade homes in order to seek shelter from disagreeable climatic conditions, mainly summer droughts and winter storms. This study refuted the widespread belief that Argentine ants invade homes solely to seek out food sources. However, other studies have found that Argentine ant infestations are common during the fall because their natural food source, honeydew, becomes scarce when temperatures begin to drop.
Argentine ants are incredibly difficult to control because most pesticides are designed to eliminate ant colonies that contain only one queen. Baiting systems are favored by pest control professionals for Argentine ant control, but baiting for these pests is also quite complicated since their food preferences vary throughout the year. Protein-based baits are best for controlling Argentine ants during the spring and early summer, but many pest control professionals claim that these pests will readily take liquid sugar baits year round.
Have you ever experienced an Argentine ant infestation?