What is a common indicator of a termite infestation?

A common indicator of a termite infestation is the presence of mud tubes along walls or foundations. Termites, particularly subterranean species, build these tubes as they travel between their underground colonies and the wood sources that they consume. These mud tubes serve multiple purposes: they protect termites from predators and environmental conditions, such as dryness, while also maintaining the necessary humidity levels that termites need to survive.

Finding mud tubes is significant because it suggests that termites are actively foraging for food, and their presence could mean that there is a risk of damage to wooden structures in the vicinity. The construction of these tubes is a direct behavior associated with subterranean termites, making them a reliable sign of an ongoing infestation.

The other options do not relate directly to termite behavior or infestation indicators. Beehives and fruit flies are not associated with termite activity, and brown patches in the lawn could result from various factors unrelated to termites.