What is the primary method for controlling subterranean termite populations in an existing structure?

The primary method for controlling subterranean termite populations in an existing structure is soil treatment. This method involves applying chemical termiticides to the soil surrounding and beneath the structure to create a barrier that prevents termites from entering the building. Soil treatment effectively targets the subterranean termites since they live and travel through the soil. It can also disrupt their colony activity, significantly reducing the likelihood of infestation.

Soil treatments are particularly crucial for existing structures because they address the direct access points for termites. These treatments can either be applied as a barrier treatment or as a baiting system, depending on the specific situation and severity of the infestation. Moreover, soil treatment can be a long-lasting solution, providing ongoing protection against future infestations by creating a chemical barrier that can last for years with proper application.

Other methods like physical barriers and wood treatment might play roles in prevention or secondary aspects of pest management but are not primarily used for controlling existing infestations in the same direct and effective manner as soil treatment. Trapping is generally used for monitoring or assessing infestation levels but is not a primary control method.