Pharaoh Ant

Monomorium pharaonis is a 2 mm pale yellow tropical ant of unknown origin (likely West African) that has become one of the most globally widespread indoor invasive pests. The species' biology defeats traditional pest-control approaches. Pharaoh ant colonies practice 'budding' (also called fission): when stressed by disturbance, predator pressure, or pesticide exposure, the colony splits — workers carry larvae and queens to new locations and establish satellite colonies, often within the same wall void or building. Spraying a visible trail therefore typically multiplies the infestation rather than controlling it. Pharaoh ant colonies are also polygynous, containing dozens to hundreds of queens; killing the workers and the visible queen leaves many other queens producing brood. The only effective control is bait-based: slow-acting toxicants in protein and carbohydrate baits that are fed back to the colony's queens over weeks. Pharaoh ants are a major hospital pest in temperate regions because indoor heating allows year-round breeding; they have been documented vectoring Salmonella, Staphylococcus, Streptococcus, Pseudomonas, and other pathogens through sterile fields, IV lines, wound dressings, and burn-unit equipment. The species is now established on every continent except Antarctica.