Which of the following is NOT a common sign of termite activity?

Wood swelling is not a common sign of termite activity. Termites primarily cause damage by eating wood and can create small holes or tunnels as they consume the material. Discarded wings often indicate that swarming termites have been present, as they shed their wings after mating. Termite frass, or droppings, is another clear indicator of active infestations, as it is a sign that termites are feeding on wood and have been living in the area. In contrast, wood swelling can result from moisture damage or other conditions but does not specifically correlate to termite presence. Therefore, recognizing the signs of termite activity is crucial for accurate assessment and treatment; however, swelling in wood is associated with various forms of deterioration, not exclusively with termites.