What is often the first sign of a termite infestation in a building?

Swarmers or alates are often the first sign of a termite infestation in a building because they are the winged reproductive adults that leave their colony to mate and establish new colonies. These swarmers typically emerge during certain seasons, primarily in the spring, and are attracted to light, which often leads them to enter homes in search of suitable places to start new colonies. Their presence can indicate that a nearby colony is established and that there is a risk of infestation within the structure.

While wood damage may become evident as the infestation progresses, and frass accumulation—termite droppings—can also be observed, these signs usually appear after the initial infestation has taken hold. Unexplained moisture can sometimes contribute to a conducive environment for termites but is not a direct indicator of their presence. Therefore, the emergence of swarmers is the most immediate and recognizable indication that termites are present.