Sainte-Julie, one of the most populous cities on the South Shore, has experienced sustained residential expansion in recent years, particularly in the Lachenaie and La Plaine sectors. This urban densification creates conditions conducive to the appearance of anthills near buildings, especially in apartment buildings where the multiplication of entrances, terraces and shared green spaces complicates pest management. We were mandated to intervene in such a building in Sainte-Julie, following repeated reports from tenants who had been observing ants in the kitchens and corridors on the ground floor for several weeks.
Diagnosis of the situation
The initial inspection identified two active anthills outside the building, one in a dirt space between the parking lot and the main entrance, the other under a storage lean-to attached to the foundation. The species involved were sweet ants (Tapinoma sessile), easily recognizable by the coconut-like smell they give off when crushed. These ants are particularly problematic in multi-unit buildings because they actively seek to get indoors to find food and sources of moisture, especially under sinks and behind refrigerators.
The building manager had already tried to apply over-the-counter products, but without lasting success: the ants systematically returned after a few days. This is a classic finding when the nest itself is not treated and only the workers on the surface are eliminated. The core of the colony, with its breeding queens, remains intact and resumes its activity quickly after each superficial treatment. Commercial products are often insufficient in the face of well-established colonies in a multi-unit building, because they do not penetrate deep enough to reach brood areas located several tens of centimetres underground.
Intervention protocol
Our team has set up a protocol in three successive steps. Firstly, direct treatment of the outer nests by injecting liquid insecticide into the identified galleries, in order to reach the brood areas and the queens. Second, the installation of bait stations around the perimeter of the building, positioned at the corners of the foundation and along the observed transit areas. These stations contain a sweet bait carried by the workers to the breeding queens. Third, residual barrier spraying along the foundation wall and door sills to slow intrusions during the colony removal phase.
Our team of exterminators in Sainte-Julie is familiar with the particularities of multi-unit buildings in the region and always adapts its methods to the context of each building. For an overview of other successful interventions of the same type, consult this implementation file on the management of anthills in buildings as well as this case study involving ants in a residential context.
Preventive measures for the condominium
Following the intervention, we submitted a detailed report to the building manager with preventive recommendations adapted to the common areas:
- Seal foundation cracks and gaps around ducts entering the building.
- Replace the dirt around the parking lot with a mineral coating or crushed stone aggregate that is less conducive to nesting.
- Educate tenants not to leave food or garbage open in common areas and on balconies.
- Inspect the storage lean-to regularly, especially under wooden pallets and behind recycling bins.
The page dedicated to the destruction of anthills on our site describes all of our methods and the species treated in Quebec. For buildings that want to incorporate long-term protection, our pest prevention plan offers structured seasonal monitoring, ideal for condominiums and managers who want to avoid recurrences. This program includes a professional inspection in the spring, before the new colonies hatch, as well as a preventive perimeter treatment in the fall to limit the risk of infestation in the following season. Our extermination company supports many property managers on the South Shore in this proactive approach, with scheduled inspection visits and a quick response to new reports.