Field plate · Tapinoma sessile
Odorous house ant
Tiny dark ants that trail to any sweetness in the kitchen — and smell of rotten coconut when crushed.
Plate 11 of 28. Drawn in profile to the identification marks named below; the scale rule is a drawing convention — sizes are given in the text.
Identification marks
Workers 2–3 mm, brown to black, with an uneven thorax profile and a waist node hidden under the abdomen. The coconut-rancid odour on crushing is diagnostic and unforgettable.
Look-alikes it is confused with
Little black ants and pavement ants (both lack the odour; pavement ants nest in soil under slabs and push up small sand mounds), and pharaoh ants in heated commercial buildings.
Where it hides in a house
Under mulch and stones outdoors; indoors in wall voids near water — under sinks, around dishwashers, in bath walls — and they shift the nest readily when disturbed, including after a spray.
Health & property risk, stated plainly
A food-contamination nuisance rather than a health hazard, famous for sheer persistence: a single structure can hold many queens and many linked nests, which is why one treatment rarely ends it.
What actually works
Sweet gel or liquid baits on the trails, left undisturbed for days while the colony feeds; sanitation of syrups, pet bowls, and recycling; caulking entry points at pipes; trimming vegetation off the walls. Patience is the method.
What doesn't
Repellent spray on the trail — it fragments the colony into more nests in more walls, the exact outcome the species is built for.
When to call a licensed pro
Call a pro when trails return every summer across several rooms, or when the nest is plainly inside a wall and baiting alone is not reducing numbers after two weeks.