What is a sign of carpenter ants' activity in wood?

A sign of carpenter ants' activity in wood includes exit holes and frass. Carpenter ants excavate wood to create their nests, which results in small holes through which they exit. Frass, which is a mix of wood shavings and other debris, is often found near these exit holes. This combination of evidence is a clear indicator of their presence and activity within the wood.

While rustling sounds may indicate movement within the wood, they are not a definitive sign of carpenter ant activity. Sawdust piles may suggest wood damage, but carpenter ants produce frass rather than sawdust. Additionally, having no visible signs would indicate a lack of activity or infestation, which does not align with identifying signs of carpenter ants. Therefore, the presence of exit holes and frass is the most reliable indicator of carpenter ants actively tunneling and nesting in wood.