A manager of an eight-unit apartment building located in Varennes, on the South Shore, contacted our team after several ground-floor tenants reported black ants in their kitchens and bathrooms. The problem, initially reported as isolated to two apartments, turned out to be much more widespread during the complete inspection of the common areas and technical rooms. The occupancy density of an apartment building creates particularly favourable conditions for the proliferation of ants, and the neighboring city of Chambly has similar problems in its high-density residential areas.
Diagnosis in a multi-unit context
Our technician inspected each of the eight units as well as the basement, boiler room, and exterior perimeter of the building. The species identified was the pharaoh ant (Monomorium pharaonis), recognizable by its yellowish color and small size. This species is particularly problematic in multi-residential buildings because it forms multiple satellite colonies that are linked together, allowing it to redistribute quickly in the event of disturbance. The main entry point was located at the plumbing pipe passage through the concrete slab in the basement. Active tracks were observed going up the heating pipes to the upper floors. For this type of complex case, our approach to house ant extermination must be coordinated across the entire building simultaneously to avoid the dispersal of colonies to untreated units.
Coordinated treatment strategy
In the case of the pharaoh ant, the use of indoor repellent insecticides is strongly discouraged because it causes a phenomenon of colonial fragmentation: the colonies split and migrate to new areas, aggravating the problem. The recommended treatment is exclusively based on non-repellent baits that the workers naturally distribute through the nest network. Specialized bait stations have been installed in each unit, in the technical areas and along the tracks identified in the common areas. This approach requires patience: the complete elimination of a pharaoh ant infestation in a building can take several weeks, as the formula must reach all the breeding queens scattered in the different satellite colonies. The manager was clearly informed of this delay in order to avoid any attempt at parallel intervention that could have compromised the treatment. You can consult a similar realization in house ants in another residential context on the South Shore to compare approaches.
Caulking and recommendations for rental management
In parallel with the treatment, our team caulked the entry points to the basement, particularly around the plumbing passages and cracks in the concrete walls. Seals were applied to the base of the pipes to cut off internal migration pathways. Written recommendations were given to the manager for tenants: maintain the cleanliness of kitchen surfaces, repair any leaky faucets without delay, properly ventilate bathrooms, and avoid storing unprotected food. These measures reduce the attractiveness of the building for pharaoh ants, which are very attracted to moisture and sugary residues. A schedule of follow-up visits was established to monitor the progress of the treatment over a six-week period, with adjustments as needed based on the activity observed.
Long-term results and follow-up
After five weeks of treatment with the bait stations, ant activity had decreased significantly in all units. By week six, no new leads were visible in the common areas or in the ground floor units. The matter was declared resolved at the end of the follow-up, and the manager opted for an annual pest prevention plan to avoid the recurrence of this problem or the appearance of other undesirable species in the building. For any pest control needs in the Varennes region and its surroundings, do not hesitate to contact our extermination company. We work in private residences as well as in rental buildings and businesses on the South Shore. Also consult our realization in carpenter ants to discover the particularities of treatment according to the species in question.