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Carpenter Ants

Identification, Habits, and Control
Closeup photo of a Carpenter Ant on white background

About Carpenter Ants

Genus: Camponotus spp.

Carpenter ants are large ants that nest in wood and are often mistaken for termites due to the damage they can cause. Unlike termites, they do not eat wood—instead, they excavate it to create smooth tunnels for nesting, which can weaken structures over time.

These ants are commonly found in areas with excess moisture, such as around leaks, damp wood, or decaying structures. While they typically nest outdoors, they can expand into homes and businesses, making them a persistent problem if not properly addressed.

How to Identify Carpenter Ants

Size

  • Workers range from 1/4 to 1/2 inch long
  • One of the largest ant species found in the U.S.
  • Winged swarmers (reproductives) are larger and may be seen during mating seasons

Color

  • Usually black, but may also appear reddish-black or brown
  • Some species have a combination of red thorax and black abdomen

Identifying Characteristics

  • Large ants with a single node (waist segment)
  • Rounded thorax when viewed from the side
  • Excavate smooth, clean galleries inside wood
  • May leave behind small piles of sawdust-like material (frass)

Where You’ll Find Them

  • Inside walls, window frames, and structural wood
  • In damp or decaying wood, especially near leaks
  • Tree stumps, logs, and woodpiles outdoors
  • Around roofs, gutters, and crawl spaces with moisture issues

Behavior and Risks

Carpenter ants prefer to nest in moist or damaged wood, which makes areas with water intrusion especially vulnerable. While they often begin nesting outdoors, colonies can expand indoors in search of additional shelter or food sources. Over time, their tunneling can weaken wood structures, particularly if left untreated.

You may notice faint rustling sounds inside walls, increased ant activity at night, or piles of frass near nesting areas. Winged carpenter ants may also appear indoors, which is often a sign of a mature colony nearby.

Although they do not pose the same level of structural risk as termites, carpenter ants can still cause significant damage if colonies grow and spread within a structure.