Carpenter Ants

Carpenter Ants in the Home


Scientific Classification: Camponotus spp.

Class: Insecta; Order: Hymenoptera; Family: Formicidae


Carpenter ants are pests that nest in wood. Outdoors, the insects live in hollow trees, logs and stumps, where they facilitate the breakdown of dead or decaying wood and prey on other pests. However, carpenter ants often enter indoor areas to look for food or nesting sites. In fact, the potentially destructive insects rank among the most common pest species of ants in the U.S. Named for their habit of excavating nests out of wood, carpenter ants cause property damage when they tunnel through the frameworks and timbers of homes.


What Do They Look Like?

carpenter ant worker
photo credit:Univ of Minn
carpenter ant closeup
Carpenter Ant

Larger than other common ant species, carpenter ants vary in size depending on their role within the colony.

Worker ants typically measure between 1/8 and 1/2 inches (3.5-13 mm) in length, while the winged reproductives and queens are usually about 3/4 inches (19 mm) long.

Carpenter ants generally range in color from black to brown or red. The most common species is the black carpenter ant, while other species boast a combination of dark and reddish colors.

In the western United States, the most frequently occurring species of carpenter ant is dull black in color with reddish legs and golden hairs on the abdomen.

top view
carpenter ant top view

Often mistaken for termites, carpenter ants differ from their wood-boring counterparts by having elbowed antennae and a constricted waist that connects the thorax with the abdomen.

Workers are polymorphic, which means they encompass a wide range of sizes.

Carpenter ant queens have large front wings.

Geographic Range

Where Are They Found in the US?

Together, the nine species of carpenter ants found in the United States cover the entire country. The pests tend to inhabit regions with cool, damp climates most commonly. Black carpenter ants live in the eastern part of the country while the western carpenter ant populates the West Coast and Rocky Mountain areas.

Why Are They Here?

Things that Attract Carpenter Ants to Houses
Contrary to popular belief, carpenter ants do not infest homes to eat wood. Instead, the pests tunnel through moisture-damaged wood for shelter. Workers forage for foodstuffs inside homes to carry back to main nests.


What Do They Eat?

In their natural environment outdoors, carpenter ants primarily feed on the sugary honeydew that aphids and similar insects secrete. The omnivores also consume plant saps and dead or live insects.

When they forage for food indoors, carpenter ants tend to prefer sweets, proteins and fats.

They feed on household products such as

  • fruit
  • syrup
  • honey
  • jelly or jam
  • candies
  • meats
  • grease
  • bread crumbs
  • pet food

Foraging carpenter ants follow a regular trail that can be traced back to the nest.

Life Cycle

During late spring and early summer, mature carpenter ant colonies of at least 2,000 members produce winged reproductives called swarmers that emerge from the old nest and leave to mate and establish new colonies.

After mating, the male dies while the newly fertilized queen locates a suitable piece of wood, excavates a nest and lays between 15 and 20 eggs.

The first generation of offspring hatches in about two months and takes another three months to develop into adults. Carpenter ants reach adulthood only after completing the larval and pupal stages of the life cycle.

As adults, the older generations of worker ants forage for food, maintain the nest and care for the future generations of offspring produced by the queen whose sole responsibility is to lay eggs.

Once the colony matures and becomes large enough, swarmers emerge to begin the mating process anew. Carpenter ants remain active during warmer weather and hibernate during winter although inside, they can remain active year round.


Where Do You Find Them?

  • Nests: Look for nests in moist or decaying wood near plumbing leaks, window sills, porch pillars, wall voids, bathtubs and showers, leaky appliances and similar locations.
  • Walls: Listen for the rustling sounds of active carpenter ants in the walls.
  • Dust: Look for piles of sawdust-like shavings discarded by excavating carpenter ants and sometimes mixed with the debris of insulation and dead insects.
  • Trails: Watch for foraging trails in the basement, attic, garage and outside, especially between the hours of 10:00 p.m. and 2:00 a.m. during the summer. Be on the lookout for winged swarmers during the early part of the spring.

Problems Caused by Carpenter Ants

Carpenter ants steal food and damage property. When the pests invade homes, they establish foraging trails and feed on various household foods.

Wood Damage
The more serious problem caused by carpenter ants, however, is the damage they inflict on wood. During the process of building a nest, carpenter ants excavate the spring wood found between the rings of hard wood in timbers. Although the pests mainly attack moist or damaged wood, they can excavate structurally sound wood as well. The level of damage caused by carpenter ants generally varies according to the number of nests in the building and the longevity of the colony.

Signs of Infestation

While the presence of foraging workers indicates the existence of a nearby infestation, the nest itself could either be inside the building or somewhere outdoors.

A stronger sign of a carpenter ant infestation is the presence of winged reproductives or swarmers inside the home which means the nest is probably also indoors.

Other signs of infestation include the piles of wood shavings the pests discard during excavation and the rustling noises produced by their activity in walls and ceilings.

More ways to tell if you have carpenter ants.

Prevention Tips

How to Keep Them Away
Attracted to damp and poorly ventilated areas, carpenter ants establish satellite colonies inside homes. Their extensive tunnel systems are regularly found under porch pillars, in timbers, insulation, window sills, and door casings.

To prevent a carpenter ant infestation, steps must be taken to discourage the pests from entering the home in the first place. Repair plumbing leaks around the house, and replace any moist or rotting timber with undamaged, treated wood.

Keep damp areas properly ventilated to prevent moisture from accumulating and turning formerly dry wood into prime nesting sites for carpenter ants. Make sure the grade of the ground allows water to flow away from the building or residence. Ensuring that attics and crawlspaces are well ventilated and clearing gutters of debris on a regular basis can help prevent moisture damage that makes the wood within a house attractive to carpenter ants.

Wood Against the House
Preventing tree branches from touching the outside of the home can help restrict access to the structure, while storing firewood in a dry place away from the house may also reduce the chances of an infestation. Refrain from putting mulch directly against the foundation. Remove and relocate stumps, scrap wood, and logs within 100 yards of building foundations.

How to Get Rid of Them?

Tips for Removal

  • Find moisture sources: Conditions conducive to water buildup can attract ants and many other pests as well.
  • Move wood piles: Wood or wood-based products should be stored at least a foot away from the home. An infestation in a wood pile can quickly become an infestation in a home.
  • Mind your mulch:Mulch can enhance the appearance of your yard, but it is often a harborage for many insects

Permanent Control
Removing carpenter ants from the home can be a challenging undertaking.

Over-the-counter removal techniques can be sporadically successful but are often ineffective in the long-term without the expertise of professional pest control. These pests prefer honeydew secreted from aphids found outside during the season as opposed to baits.

Targeted insecticidal treatments typically resolve infestations quickly.

Furthermore, in addition to the main colony carpenter ants often establish multiple satellite nests within the same area. Complete control can only occur when all the nests are located and treated.

Pest management professionals know how to find carpenter ant nests and have the most effective tools for eliminating the pests completely. If a carpenter ant infestation occurs, count on a professional pest management service to take care of the problem knowledgeably and successfully.