An owner of a small commercial building located in an industrial area of Sherbrooke, in the Eastern Townships, contacted our team after several tenants reported the aggressive presence of hornets at the main entrance of the building. The nest, hidden in the cavity of an exterior insulation board, was not visible from the outside, but the intense activity of insects around the aluminum soffit betrayed their presence. For a building that receives daily deliveries and visitors, the situation represented a serious risk that could not be ignored.
Situation assessment and response planning
In Sherbrooke, a large city in the Eastern Townships located at the confluence of the Saint-François and Magog rivers and an important regional and economic hub, commercial buildings with composite cladding often have wall cavities ideal for hornet nesting. Our technician performed a complete inspection of the perimeter of the building, including the roof terrace accessible through an interior hatch. The main nest was located inside the insulation board, about sixty centimetres from the opening in the soffit. The size of the colony, estimated from the observed movement flux over a thirty-minute period, indicated a well-developed population corresponding to a mid-season nest.
Given the limited access to the cavity and the regular presence of people on the site, our extermination team in Sherbrooke planned the intervention outside of business hours, in the early morning before the arrival of the employees. This precaution is standard for any commercial treatment to minimize the risk of exposure to bystanders.
Colony treatment in a confined space
The reduced access to the wall cavity led to the choice of an injection of expanding insecticidal foam, applied via a small diameter service hole drilled in the insulation board. This type of approved product gradually fills the internal space, coating the combs of the nest and the hornets there. The insecticidal effect on contact and inhalation ensures effective removal even in areas where the standard sprayer cannot reach. For our hornet extermination service, this confined environment protocol is regularly used on buildings with heavy structures.
The next morning, a control inspection confirmed the total cessation of activity. The insulation board was opened over a restricted area in order to physically remove the nest and inspect the condition of the interior structure. No significant damage to the vapour barrier was noted. The debris was removed and the open section was closed with materials compatible with the existing façade system. This physical removal step is important: an abandoned nest in place can become a site of attraction for new colonies the following year, attracted by residual pheromones imbued in the nest’s construction paper. In a commercial environment, where the same façade remains in place for many years, this precaution is particularly relevant.
Corrective actions and prevention plan
To avoid a recurrence in the following seasons, our technician identified several potential entry points along the junction between the soffit and the façade. An exterior insect treatment was carried out on the entire periphery of the building, including an application of repellent product on the surfaces where hornets tend to build their first nest cells. This surface treatment acts as a temporary chemical barrier during the critical colony-founding weeks in the spring.
The owner was also informed of the importance of keeping the expansion joints and façade fittings in good condition. Small cracks and gaps under gutters are prime access points that are frequently found on commercial buildings of this generation. Our technicians have identified and documented each of these points to facilitate preventive maintenance work.
This type of intervention on commercial buildings is documented in several of our projects, including this case on the South Shore and this one concerning wasps in the workplace. Nova Extermination is able to ensure the annual monitoring of your commercial property with a preventive visit each spring, before the active nesting period, in order to maintain a safe work environment for all your occupants. Commercial building owners who invest in regular monitoring enjoy valuable peace of mind and avoid the costs and disruption associated with emergency response during peak season, when colonies are at full maturity and hornets are at their most aggressive.