An apartment building located in the Saint-Laurent sector of Longueuil, on the South Shore of Montreal, called on our services after several tenants reported the presence of tiny yellowish ants in their kitchens and bathrooms. Pharaoh ants, recognizable by their tiny size of about one to two millimeters and their characteristic amber color, are one of the most difficult pests to control in multi-unit buildings. Their ability to form new colonies by splitting, i.e. dividing when they feel threatened, makes conventional treatments ineffective, if not counterproductive. The intervention of our certified exterminator on the South Shore made it possible to resolve the situation definitively thanks to a methodical approach that is perfectly adapted to this type of infestation in multi-unit buildings.
Thorough inspection of the premises
As soon as we arrived in Longueuil, our technician carried out a complete inspection of the building, unit by unit, paying particular attention to high-risk areas. Pharaoh ants like warm, moist places close to food sources. In this twelve-unit building, the settlements were concentrated in the walls between the kitchen on the ground floor and the bathroom on the first floor, as well as in the false ceilings of the central corridor. The inspection revealed that cracks in the plumbing joints allowed ants to move freely from one floor to another, a very common scenario in buildings built before 1990. Active tracks have been spotted along the heating pipes and in the grooves of the window frames. This precise mapping of the areas of activity is essential before any intervention, because placing bait in the wrong places only results in dispersing the colonies rather than eliminating them. Our extermination team in Longueuil is familiar with this type of building built in the 1980s, where the wall cavities provide the pharaoh ants with a real internal circulation network. Homes in the nearby Greenfield Park area have similar problems, highlighting the importance of acting quickly to prevent the spread.
Gel bait treatment strategy
The method of choice for the extermination of pharaoh ants in a residential building is the use of slow-transfer insecticide-based gel baits. This approach is based on a simple but frighteningly effective principle: the workers collect the bait and bring it back to the colony, where it is shared with the other members, including the queens. The elimination process takes a few weeks, but it reaches the colonies nestled in inaccessible cavities. Our technicians placed small doses of gel bait at regular intervals along all active tracks identified during the inspection, including countertop cavities, behind appliances, under sinks, and along pipe columns. It is crucial not to spray insecticides in parallel, as this will repel ants and compromise the effectiveness of the bait. The tenants were informed of this instruction and cooperated by avoiding the use of strong cleaning products near the baiting points for the duration of the treatment.
Monitoring, bait renewal and results
Two weeks after the initial installation, our technician came back to assess the consumption of the baits and adjust their positioning. Some points had been entirely consumed, confirming the sustained activity of the colonies. New baits have been placed in these areas, and discreet monitoring stations have been installed in the common areas. By the fourth week, ant activity had decreased significantly in the majority of homes. During the final control visit, in the sixth week, the tenants no longer reported any visible presence. To consolidate the results, we recommended that the owner have caulking done at the entry points identified during the inspection, particularly around the pipe passages and in the cracks in the foundation. Similar work carried out in comparable buildings, as evidenced by our construction in a multi-unit building, confirms that this combination of treatment and sealing gives the best long-term results.
Prevention to avoid recurrence
Pharaoh ants are persistent pests that can reappear if favorable conditions are not eliminated. We have given the building manager a prevention guide adapted to the rental context. Key guidelines include: promptly repair any water leaks, do not leave food exposed in common areas, store food products in airtight containers, and notify the manager at the first sighting of ants so that they can intervene before the colony expands. A pest prevention plan tailored to apartment buildings can also be put in place to conduct seasonal preventive inspections, an approach that is particularly effective in large residential buildings. This proactive approach protects tenants, public health and the value of the building on the market. The combination of rigorous professional treatment, sealing of access roads and maintained collective hygiene is the strongest guarantee against reinfestation in a collective housing context such as that of this Longueuil building.