Dealing with Carpenter Ants

By Robert Robillard on Home Maintenance, How To

Carpenter Ant Treatment For Your HomeDealing with Carpenter Ants

Ants are interesting creatures.   Did you know that an ant can carry 50 times its body weight?

Accepting that ants live in nature is one thing but having them live in your home is another.  No matter how you feel on this topic I’m sure you prefer not to have an ant problem in your home.  Dealing with Carpenter Ants can be tricky so read on.

As a renovation contractor I see Carpenter Ants in just about every home I work on, mostly around damp wood as a result of water intrusion or lack of proper maintenance. When you think about the fact that there are 1.5 million ants on the planet for every person then it’s easier to understand why I see so many ants.

The most common types of ants that you see inside a home are:

  • Carpenter Ants
  • Acrobat Ants
  • Pavement Ants
  • Odorous House Ants

Each ant has unique characteristics that may affect the best way to control them but there are some very common methods you can deploy on you own.  When dealing with ants it’s best to first take a moment to understand what they are and what their up to before trying to control or eradicate them.

Dealing with Carpenter Ants Video

Carpenter Ant Characteristics

Carpenter Ants live in colonies, which can range in size, from hundreds to millions depending on the species.  Carpenter Ants establish their colonies in galleries excavated from damp or damaged wood.  Carpenter ants do not eat wood as termites do, but instead remove wood and deposit the debris outside of their nests in small piles.

Carpenter ants vary in size and color, most are black and range from 3.4 to 13 mm in length.  The life cycle of a carpenter ant is estimated to be 6 to 12 weeks from egg to adult.

Each colony has one or more queen ants whose primary job is to reproduce “worker ants,” and every ant colony has a hierarchy structure with certain job functions.   Smaller satellite nests consist of workers, older larvae and pupae.

Workers feed and care for the queens and developing ants, and are the ones seen foraging for food and water, often at great distances from the colony.  These ants lay down invisible odor trails, which the workers follow back and forth between food and the nest.  Sometimes you can even follow a trail of ants back to a nest from a food source.

Typically in the spring time some ant colonies produce swarmers which are winged ants. These winged ants leave the colony to mate and establish new colonies.  It takes three to six years to establish a large and stable colony.

Behavior, Diet & Habits

Carpenter ants reside both outdoors and indoors in moist, decaying or hollow wood.  They DO NOT eat wood; they bore holes and galleries in wood to a series of tunnels to form their nests and provide passageways for movement within their nest.  The tunneling produces wood shavings mixed with parts of dead ants which provides clues to nesting locations.

Carpenter ants do not eat wood, but they will feed on a variety of food people eat—particularly sweets and meats. They will also feed on other insects.

Signs of a Carpenter Ant Infestation

Carpenter Ant workers and swarmers are the most likely sign you will see around your home.  The worker ants will observed foraging for food. Swarmers usually are produced when a colony matures and is ready to form new colonies. These winged ants often indicate a well-established colony, and are often mistaken for termites.

Another indication of carpenter ant infestation will be the debris they produce from tunneling in the wood. Rough wood shavings mixed with parts of dead ants from the colony indicate carpenter ant nesting activity.

Controlling Carpenter Ants

When dealing with ants eliminating the egg-laying queen ants and the nesting ants hidden somewhere in the structure is the key to effective ant control.

In my experience, I see ant nests in hidden, difficult to access spaces behind walls, cabinets, and appliances; behind window and door frames; and beneath floors and concrete slabs and in wet wood.

When dealing with ants and the location of the ant nest is unknown or inaccessible, it is best to us an insecticide bait.

The advantage in using baits is that foraging ants take the insecticide back to the nest and feed it to the queen(s) and other colony members. As a result, the entire colony often is destroyed. Most baits sold to homeowners come pre-packaged with the insecticide and food attractant confined within a plastic, child-resistant container.

Dealing with Carpenter Ants

Effective Carpenter Ant Control Baits:

Some of the more effective ant baits, sold in grocery and hardware stores, are Terro® Insect Bait, Combat® Quick Kill Formula bait stations and Combat® Ant Killing Gel; Raid Ant Bait II, and Terro® Ant Killer II.  Follow all manufacturer recommendations on use and application.

Ants are drawn to the sweet ingredients in the insect bait. The bait, which is typically Borate based, has a delayed effect on ants, allowing time for them to eat it, carry it to back to the colony and share it. This slow kill allows time for the foraging ants to make several trips to the bait and deliver more poison to eradicate the entire colony- including the queen.

It is suggested that you place the bait in the path of observed ants.  Remember that the ants follow their invisible odor trails back to the nest. After a week or so if the presence of ants does not diminish try using a different ant bait.

Best results require a sustained period of feeding. If you feel the baits did not work a professional pest control firm has a wider selection of bait products not available to the public, such as Advance™, Maxforce®.

Common insecticides in Carpenter Ant baits are listed below.   Be sure to select a product that is labeled for ants.

  • abamectin
  • fipronil
  • sulfluramid (may be listed as N-ethyl Perfluorooctanesulfonamide)
  • disodium octaborate
  • orthoboric acid
  • propoxur (e.g. Baygon)

Professionals also have a larger arsenal of sprays and insecticide dusts which can be effective against ants, including Termidor®, Phantom®, Demand®, Talstar™, and Suspend®.

 Carpenter Ants Nesting Outdoors

Seventy five percent of all main carpenter ant nests are located outside the house, where there is abundant moisture. There may be one or more smaller [satellite] nests inside your house. These smaller nests are most frequently found inside walls, in ceilings, under outdoor siding, in wood near foundations, near downspouts or roof gutters, in floors (particularly bathrooms), or in insulation.

Carpenter Ants noticed inside the home may actually be nesting outdoors in the yard.

Yard Inspection

When carpenter ants nest outdoors, they are often found in in these locations:

  • Hardwood trees that contain holes and other imperfections
  • Moist or rotten wood.
  • Stumps
  • Wood piles
  • Ant hills

Dealing with Carpenter Ants

House Inspection

The most obvious sign of carpenter ant infestation is the presence of workers inside a building or home,  ants can be tracked by points of entry.  Carpenter ants typically seek wood that has been softened by moisture, decay or other insects.  Look in places such as:

  • Attic vents
  • Foundations [Foundation and house seam]
  • Cracks
  • Electric and telephone wire penetrations
  • Pipe penetrations
  • Behind rotting siding and trim
  • Between window and door framing  [Areas where roof runs of onto house]

Try to locate their trails, ants usually prefer to trail along lines and edges. When tracing ant trails indoors or outdoors, pay particular attention to cracks, seams, and edges created by baseboards, the tack strip beneath perimeter edges of carpeting, mortar joints, electrical and plumbing penetrations, the foundation- siding interface, etc.   Look for the ants themselves and for sawdust-like wood shavings or small slit openings called windows.

Maintenance and caulking of these cracks and any wall or foundation penetrations may help prevent ant entry.  Also trim back trees and shrubs so they do not touch the building.

Many times an Ant nest is easily found by locating the ant hill or mound in the ground.

Other times, the nests will be concealed under mulch, gravel, stones, landscaping timbers, pavement, or beneath the grass edge adjoining the foundation wall of the building.

Some kinds of ants prefer to nest behind exterior siding or wood trim that has been damaged by moisture.

Ant entry can be reduced by spraying liquid insecticides around the outside perimeter of the building approximately 24” out and up the foundation wall and under siding seams and utility penetrations.

Common Insecticides

Common insecticides for treating ant nests in the lawn are listed below.

Be sure to select a product that is labeled for treating lawns:

  • permethrin as a liquid or granules
  • carbaryl (e.g. Sevin) as a liquid or granules
  • bifenthrin as granules
  • cyfluthrin as granules
  • acephate as a liquid

Common insecticides for treating the building exteriors are listed below.

Be sure to select a product that is labeled for treating the perimeter of buildings’ exteriors:

  • permethrin as a liquid or granules
  • bifenthrin as a liquid
  • carbaryl as a liquid or granules
  • cyfluthrin as granules
  • deltamethrin as a dust

CAUTION: Read all label directions carefully before buying insecticides and again before applying them. Information on the label should be used as the final authority.

Using Boric Acid Powder for Carpenter Ants:

The best way to control carpenter ants is to find and destroy the nests. Recent studies have shown that carpenter ants follow distinct scent trails between the satellite colonies and the parent nest.  Carpenter ants also rely on scent trails to recruit their nest-mates to food.

If you locate an area suspected for housing a carpenter ant colony treat the area with Boric Acid. This is easier said than done as most carpenter ants live in cavities and voids like in the house walls.

House wall voids and other hidden spaces can be accessed by drilling a series of small (1/8 inch) holes and puffing Boric Acid into the cavity. If you suspect the nest is in a wall, drill and treat at least 3-6 feet on either side of where ants are entering so as to maximize the chances of contacting the nest. Carpenter ants prefer to travel along wires, pipes and edges. If you suspect the nest location is in a wall, also treat behind pipe collars and behind electrical switch plates/receptacles.


Knowing what species of ant you have in your home helps to determine the nesting site, food preference, and the best method of management. In most cases, the most effective, permanent solution to eradicating the colony is to find and treat the nest; with the goal of killing the reproductive queens.

Proper food storage and waste management will reduce the food that often attracts ants.  Sometimes having a professionals pest control specialist is the best way to treat and deal with Carpenter Ant and other ant problems.



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About the author

Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzz As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising the bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

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