The ant species most frequently encountered and successful in domestic settings across North America is the Odorous House Ant, known scientifically as Tapinoma sessile. This native ant thrives in human-modified environments, quickly establishing itself as a dominant household pest.
Identifying the Odorous House Ant
The Odorous House Ant is small, with workers measuring between 1/16 and 1/8 of an inch (2.4 to 3.2 millimeters). They are uniformly colored, ranging from dark brown to blackish-brown. A distinguishing physical feature is the single node connecting the thorax and abdomen, which is flattened and often concealed by the rear portion of the body (gaster).
The most definitive characteristic, and the source of its name, is the distinct, pungent odor released when the ant is crushed. This smell is often described as resembling rotten coconut, blue cheese, or turpentine. These ants are highly adaptable, establishing colonies in diverse locations both outdoors and indoors. Outdoor nests are typically found under stones, logs, or mulch, while indoor colonies reside in wall voids, under insulation, or behind cabinets. Foraging workers move quickly and generally follow defined trails as they search for food.
Biological Reasons for Widespread Success
The success of the Odorous House Ant in urban environments is attributed to a highly flexible and resilient colony structure. Unlike many ant species that maintain a single nest (monodomy) and a single queen (monogyny), T. sessile exhibits both polydomy and polygyny. Polydomy refers to a single colony occupying multiple, interconnected nests, allowing the population to spread out and utilize resources across a larger area. Polygyny means the colony contains multiple reproductive queens, sometimes numbering in the thousands, which facilitates rapid population growth.
This multi-queen structure makes eradication difficult, as eliminating a single nest does not destroy the entire supercolony. If a nest is disturbed, workers and queens can relocate to a nearby satellite nest, a process known as budding, ensuring the colony’s survival. The species maintains an adaptable, omnivorous diet, though they show a strong preference for sugary substances like honeydew, nectar, and household sweets.
Management and Prevention Strategies
Effective management requires a strategy focused on sanitation, exclusion, and baiting, rather than relying solely on contact sprays. Sanitation efforts must focus on eliminating attractive food sources. This includes promptly cleaning up spills, storing pantry items in airtight containers, and regularly removing trash. Removing pet food bowls when pets are finished eating is also necessary to reduce available nutrition.
Exclusion involves physically sealing potential entry points into the structure. This includes caulking cracks and gaps around utility pipes, windows, and doors. For direct control, ant baits are the most effective treatment because foraging workers carry the toxic substance back to the multiple nests and queens. Liquid or gel baits are recommended over sprays, as sprays only kill visible foraging workers and do not address the large, multi-queen colony. When baiting, avoid wiping ant trails, as the pheromone trails guide workers to the bait and back to the colony.