The smell test: the fastest ID method
Crush a single worker between your fingers. If you detect a sharp, chemical smell — described as rotten coconut, citronella, or blue cheese — it is an odorous house ant. No smell means pavement ant. This is the fastest field ID available. The smell comes from formic acid and related compounds released from the gland between the thorax and abdomen when the ant is disturbed. It is distinct and unmistakable once you have smelled it once.
Why misidentification causes treatment failure
Pavement ants and odorous house ants look nearly identical to the naked eye — same size range (2-4 mm), similar dark colouration, similar trail patterns. The difference matters because odorous house ant colonies have multiple queens and are extremely prone to budding when they encounter repellent products. A spray application that kills workers near the trail immediately triggers a colony-split response. You can go from one trail in the kitchen to three trails in three rooms within a week. The same spray on a pavement ant colony produces simple reduction without budding.
Odorous house ant biology
Tapinoma sessile is a native North American ant with broad habitat tolerance — it nests in soil, under bark, under objects, inside wall voids, in insulation, and under flooring. Unlike pavement ants, which strongly prefer soil under hardscape, odorous house ants nest readily inside structures year-round. A Metro Vancouver home with a moisture-rich basement, moist bathroom subfloor, or chronically damp crawlspace is ideal habitat for indoor odorous house ant establishment. The colonies can reach 10,000+ workers with dozens of queens in a single indoor establishment.
Correct treatment protocol
- Confirm species with the smell test — crush one worker.
- Locate all active trails — odorous house ant colonies often have multiple simultaneous trails in different rooms.
- Apply non-repellent sugar-based gel bait on all active trails simultaneously. Treating one trail while others persist allows the colony to compensate.
- Maintain bait for 21 days — odorous house ant colonies recover quickly if bait is removed before all queens are dead.
- Do not spray anywhere in the home while bait is active.
- After activity ceases, seal entry points and address any moisture in wall voids or subfloor.
The 'sugar ant' confusion
In Metro Vancouver, 'sugar ant' is used interchangeably for odorous house ants and pavement ants — and sometimes for any small ant in the kitchen. It is not a scientific name. The confusion matters because the two most common 'sugar ants' have different budding behaviour and different responses to spray. Before treating any small kitchen ant in BC as a generic 'sugar ant,' take 30 seconds to do the smell test. The ID takes less time than it takes to drive to the hardware store.
Odorous house ants in strata buildings
Multi-unit strata buildings in Metro Vancouver — particularly Burnaby and Vancouver condos and townhouses — see odorous house ant problems more frequently than detached homes because shared wall cavities allow colonies to move between units. A colony established in unit 4B can have satellite nests in units 4A, 3B, and the common-area wall cavity simultaneously. Individual unit treatment repeatedly fails when the colony root is in shared structure. Strata-wide coordinated treatment is required. Under the BC Strata Property Act, the strata corporation bears responsibility for treating infestations in common property.