In Carignan, a wooded municipality on the South Shore bordering Chambly and the Richelieu sector, a single-family residence with a finished basement was the scene of a gradual infestation of carpenter ants. The owner had initially attributed the few ants observed in the basement playroom to a one-time intrusion, without imagining that the colony had already established several satellite nests in the bathroom partitions and in the adjacent floor joists. It was only when we noticed the repeated presence of winged ants in the spring, a characteristic sign of swarming in a colony that had been established for more than a year, that the call to our team was triggered. Our team of exterminators in Carignan intervened for a complete diagnosis and integrated treatment.
Identification of the source of infestation
The inspection quickly revealed a main entrance route via a section of damp underbody, where a misaligned garden drain was directing rainwater to the foundation. This point of chronic moisture had gradually softened the joists at the edge, creating a soft wood that was easy for carpenter ants to excavate. The extermination of carpenter ants in this context required simultaneously treating the source of the problem, namely humidity, and the active presence of insects in the structure. Galleries were found in the wooden joists of the finished cellar, in the drywall studs in the basement and in the wooden frame of a basement window. The presumed mother nest was located in a portion of a decomposed wooden fence in the backyard, directly against the cedar hedge. An annex anthill had also been established in an old block of firewood stored under the back balcony.
Treatment of the finished basement and structure
The treatment of a finished basement presents the complexity of limited access to load-bearing structures, hidden behind gypsum partitions. To avoid unnecessary demolitions, the technician made small, strategic perforations in the gypsum sheets at the precise locations where the galleries had been located using an acoustic sounding, and then injected a residual powdered insecticide directly into the galleries. These openings, of small diameter, were then filled with plaster putty. In the accessible areas under the stairs and in the mechanical room, a spray of residual insecticide concentrate completed the interior treatment. Outside, the decaying fence and contaminated firewood were treated with contact and removed, and an insecticidal barrier was applied to the foundation perimeter. This type of intervention is documented in this similar realization in carpenter ants.
Fixed the humidity and caulking issue
Complete caulking of the entry points was carried out, including sealing the foundation cracks with a hydraulic mortar, sealing the gaps around the drainage pipes and replacing the deteriorated joint covers around the basement windows. A correction of the garden drain was recommended as a priority measure to eliminate the root cause of moisture in the basement. Without this correction, the degradation of the wood would continue, creating favourable conditions for a recurrence of infestation in the following seasons. The homeowner was also advised on the importance of maintaining adequate ventilation in the basement to prevent condensation, an indirect source of moisture in the lumber.
Long-term follow-up and recommendations
The five-week follow-up visit confirmed the elimination of ant activity inside the residence. The garden drain had been corrected by the owner, which had already significantly improved the condition of the basement. A personalized prevention plan was submitted, including an annual inspection recommended each spring before the swarm. Nova Extermination’s certified exterminators on the South Shore and South Shore offer this type of personalized follow-up for each case. For other comparable projects, see this case study in an anthill as well as this realization in carpenter ants in a residential context on the South Shore.