What structural indication confirms damage caused by subterranean termites?

The confirmation of damage caused by subterranean termites can be seen in the presence of frass, which is a mixture of wood and soil that is cemented together with termites' saliva. This substance is a byproduct of termite feeding and is indicative of their activity within the wood. Frass can often be found near areas where termites are active, such as near infested wood or in their nesting areas. It serves as a clear sign that subterranean termites are present and have been consuming the wood, making it a distinct indicator of termite damage.

While other signs may suggest pest activity, such as mold which indicates moisture problems or wood dust which could suggest a variety of wood-destroying insects, frass specifically ties back to the feeding habits of subterranean termites. Hollow sounds when tapping wood can also indicate infestation, but they are more related to the structural integrity of the wood rather than a direct sign of termite activity like frass is. Thus, frass with its unique composition is the most definitive structural indication of damage caused specifically by subterranean termites.