Top Signs of Carpenter Ant Activity to Watch For
Frass piles (sawdust-like debris)
Frass piles are a common and telling sign of carpenter ant activity. These debris accumulations are created as worker ants chew and excavate wood to create galleries inside structural elements. The frass is typically a dry, sawdust-like material that may include tiny wood fibers and insect fragments, sometimes with very small discarded wings. You’ll often find frass near suspected entry points such as baseboards, behind electrical outlets, around window frames, or along floor joists where ants are actively digging behind the surface. The appearance of frass indicates that a colony is already established within the wood and actively expanding its nest.
Distinguishing carpenter ant frass from other debris is important. Carpenter ant frass tends to be coarser than typical dust and contains wood fibers along with incidental insect parts; it is often deposited in piles rather than scattered dust, and you may notice a tendency for the piles to accumulate in accessible corners, gaps, or voids near the wood being gnawed. If you see frass, it’s a good sign to investigate further for a hidden nest, particularly in moist or damaged wood where ants are drawn to soften, decayed areas. While cleaning up frass can remove visible evidence, it does not address the underlying nest behind the wall, so it’s wise to assess moisture sources and potential entry points.
When frass is present, it’s time to look for other signs of carpenter ant activity to confirm a broader infestation and to guide next steps. Top signs of carpenter ant activity to watch for include: visible carpenter ants or swarmers, which are often attracted to light and can appear in spring or after rain; damaged or hollowed wood with smooth galleries that feel hollow when tapped and sound hollow to the touch; moisture damage or decayed wood, since carpenter ants seek damp, softened wood to excavate; and sounds of movement or rustling inside walls, which may indicate activity behind the surface. Seeing multiple signs together greatly increases the likelihood of an established colony. If frass piles coincide with these other indicators, it’s prudent to contact a licensed pest professional promptly. They can confirm the presence of a colony, identify the moisture sources feeding the activity, and implement an integrated approach that may include moisture control, wood repair, and targeted treatments to eradicate the nest and prevent recurrence. Prompt attention is important because carpenter ants can cause structural damage over time if left unchecked.
