Carpenter ant frass looks a lot like sawdust. It is excavated wood the ants removed to build a nest. Two ways to tell frass from other sawdust. First, the frass will have black insect parts in it. These are body parts from other dead carpenter ants removed from the nest. Second, the frass will usually be in a conical pile. This pile forms under where the worker ants drop it, but not necessarily under the nest. Carpenter ants can and will carry frass many feet from the nest opening before dropping it. For example, it may be dropped at the end of a beam, where the nest entry point is in the middle of the beam.