Final answer:
Subterranean termite damage is characterized by eating along wood growth rings and clean galleries. Wings are not commonly found in these galleries, but near entry points during swarming.
Step-by-step explanation:
You can tell damage is from subterranean termites primarily through certain telltale signs. These termites tend to eat wood so that the damage appears to be along the growth rings, and they create clean galleries within the wood which are free of debris since they use the wood as a food source.
Unlike other pests, you may not typically find wings in the galleries, as these are more commonly seen near entry points of flying termites when they swarm, not within the tunnels they create.