APPEARANCEcarpenter ants

Carpenter ants are wood-boring ants.  Unlike termites, they do not eat wood, but remove old, damp, or decaying wood in the process of building their colonies. These colonies will expand to healthy wood as the population increases. Camponotus modoc, or the Western Black Carpenter ant, is the most common species in Western Washington.  They are black with reddish legs.  Workers are wingless.


Like all ants, carpenter ants are social insects.  Colonies consist of a reproductive female (queen), reproductive males (drones), non-reproductives (workers), larvae, and eggs. The workers in C.modoc are broken down into three groups depending on size: minor (small), intermediate (medium), and major (large).  The workers excavate damaged wood to create elaborate “galleries” and tunnels as they enlarge the colony.

They collect aphid honeydew (a sweet exudate), other insects and arthropods.  They are also attracted to sweet materials such as decaying fruit and syrups.

Carpenter ants will initially nest in standing trees or logs in the forest.  From this parent nest, satellite nests can form in surrounding trees, stumps, etc.  Communication and travel is maintained between parent and satellite.  The satellite colony may contain eggs, larvae, pupae, and winged reproductives.  Trails between the colonies are maintained (2cm wide) and peak travel time occurs from sunset to sunrise. Colonies can range from ten thousand to fifty thousand in most satellite colonies to a hundred thousand in the parent.


They cut "galleries" into the wood grain to provide passageways for movement from section to section of the nest. Certain parts of a house, such as around and under windows, roof eaves, decks and porches, are more likely to be infested by carpenter ants because these areas are most vulnerable to moisture.  Because workers are produced at a slow rate, it may take two to three years from the start of a colony to when damage is noticeable.

  • Evidence of an infestation include:
  • presence of ants
  • sawdust in piles with insect parts
  • trails through grass or soil
  • rustling or tapping noises


When building a new home in a forested area, clear out all wood debris such as stumps and logs.  If possible, hire an entomologist to survey the surrounding tree line for signs of carpenter ants.  Hire a licensed pest professional to dust the wall voids of the new construction and make sure the house is properly ventilated so moisture does not accumulate causing wood damage.

In older homes, clear away any vegetation from around foundations.  Stack firewood away from the house and be cautious when spreading beauty bark as carpenter ants may hide in it and be transported from the original site to another.

There is no known biological control for carpenter ants.  Trained and licensed pest control operators must be called.  Both liquid and dust insecticides can be applied depending on the infestation.

Call a Critter Control of Seattle expert today to help control your carpenter ant problem. 206.431.6833