An apartment building owner in Greenfield Park, on the South Shore of Montreal, called on our services after several tenants reported the presence of silverfish in their respective apartments. This situation, which was more delicate than in a single-family residence, required rigorous coordination between interventions in the common areas and those in private dwellings. Greenfield Park, a residential neighbourhood in Longueuil near Saint-Lambert, has a diverse housing stock where two- and three-storey buildings built in the 1960s to 1980s are particularly vulnerable to this type of infestation because of their aging structure and shared basements.
Diagnosis in a multi-unit context
The initial inspection covered the entire six-unit building, starting with the technical basement that housed the heating room, the collective storage room and the plumbing columns. This is where the concentration of insects was highest: silverfish had colonized the dark nooks and crannies around the pipes insulated with mineral wool, a material they use as shelter and sometimes as a source of food. Bite marks on moving boxes forgotten in the common storage confirmed a well-established infestation.
In the apartments, the insects had migrated through plumbing columns and wall voids, mainly reaching the bathrooms and kitchens of the ground and first floor apartments. Tenants on the upper floors reported a less frequent, but not non-existent, presence. Our team at Greenfield Park is used to this type of complex mandate and was able to plan the treatment with minimal disruption to the residents. A similar assessment was made during a study concerning bed bugs in another building on the South Shore, confirming that multi-unit buildings require a systemic approach.
Coordinated treatment plan
Given the nature of the building, the treatment protocol was structured in two distinct phases. The first phase targeted the basement and common areas: application of residual insecticidal powder in all cracks in the concrete slab, around the plumbing columns and behind the electrical panels. A surface treatment with a professional liquid insecticide covered the walls and skirting boards of the technical room. The collective storage was emptied, cleaned and treated before being reorganised with plasticised storage materials that are less attractive to the insect.
The second phase consisted of treating each dwelling concerned, targeting the wetlands and the junction points between the walls and the floors. Strips of residual powder were applied under sinks, in low kitchen cabinets and behind toilets. Adhesive traps have been installed in dark areas to ensure follow-up between passages. All of the work was carried out using products approved by Health Canada, adapted to residential spaces. For the complete extermination of silverfish, this phased approach ensures elimination of both adult individuals and developing cohorts.
Building Sealing and Humidity Control
The owner was advised that long-term success would depend on correcting the factors that promote the infestation. A plumbing inspection revealed slight condensation on some cold pipes in the basement, creating a moist micro-environment ideal for silverfish. It was recommended that these pipes be insulated to eliminate condensation. The gasket on the back basement door, worn out and letting in moisture during rains, was replaced.
A caulking program of entry points was undertaken around the perimeter of foundation windows and around pipe penetrations in concrete walls. This work, although preventive, is essential to prevent a return of the infestation, especially in a building where the occupants change regularly and may introduce cardboard or other contaminated materials.
Follow-up and final recommendations
Two follow-up visits were performed after the main treatment. The sticky traps installed in the basement showed no new catches by the third week. The tenants had no longer reported the presence of insects in their respective dwellings. The landlord has set up a quarterly inspection schedule for the technical basement, a good practice for any apartment building located in an area of the South Shore where seasonal variations in humidity are marked.
Our certified professionals at Nova Extermination are at your disposal for any type of mandate, whether it is a private residence or an apartment building. We have also carried out comparable work in other sectors, as evidenced by our work on spiders in a similar multi-unit context on the South Shore, confirming the consistency of our method across different types of buildings.