Are Carpenter Ants Destructive?

Matthew Hess 7/11/2023

Carpenter Ant Sizes

Many people may not realize that carpenter ants are destructive. In North America, carpenter ants are the largest native species. Within the colony there are several different sizes of Carpenter ants making them a polymorphic species. Carpenter ants have black or reddish bodies and reach lengths from 1/4 inch up to 1/2 and even 5/8 inch (the diameter of a dime). Their larger size makes them easily identifiable from other, smaller species.

Carpenter ants can range in size from 1/4 inch up to 5/8 inch. Queens will be even larger. Their variety of sizes within a single colony makes them polymorphic.

Within a single colony, carpenter ants can range from 1/4 – 5/16 inch up to 5/8 inch for workers and queens can be larger. This makes the carpenter ant polymorphic and sets them apart from many other monomorphic species, further helping identify them.

Polymorphic ants are easily distinguished from monomorphic ants

Carpenter Ant Eggs

Carpenter Ant Diet

Contrary to what many believe, carpenter ants do not actually consume wood, although they are destructive. Instead, they excavate it. This can result in piles of sawdust near entry and exit holes. Carpenter ants do not have the necessary digestive enzymes to break down cellulose materials like termites. Termites, on the other hand, do have the proper enzymes and they actually consume the wood as they excavate, leaving behind no sawdust piles.

Carpenter ants excavate wood but do not consume it.

This wood is damaged by carpenter ants, possibly after termite damages had already occurred.

Instead of eating wood, carpenter ants consume a diet consisting of a wide range of plant and animal matter. This included honeydew produced by aphids. Additionally, they eat the bodily fluids of live and dead insects, which is protein based. As many homeowners can attest, they will also consume household foods including starches, sugars, proteins and even seeds.

Interesting Behaviors

One of the most interesting and underrated behaviors of carpenter ants is that they will claim, excavate and inhabit old termite damage galleries in wood. They can do their own damage as well by boring into wood and their galleries can look similar to the untrained eye. However, there will be significant differences upon closer investigation.

Carpenter ants will excavate old termite galleries in wood and claim them for their own colony

Excavated termite galleries will be cleaned, smoothed and enlarged for the carpenter ant colony.

While termite galleries are somewhat jagged and contain a rough texture, carpenter ant galleries are smooth. Once termite galleries are claimed by carpenter ants, they will clean the galleries of any debris, smoothing them out as they go. The refuse they remove during excavation is pushed out of the galleries with sawdust from their further excavation. Their refuse will contain materials like uneaten food particles, dead insects, fecal pellets, excavated wood particles (sawdust) and dirt and debris from old termite galleries.

Carpenter ants leave behind a clean, smooth gallery or galleries, after their excavations.

The galleries of carpenter ant damage, as seen here, are very smooth in appearance, with no jagged edges.

Termites do a far deal greater amount of damage than carpenter ants but both can pose serious structural problems if left to their own devices. Both require a certain amount of moisture and therefore search for similar sources of decaying wood. This means that often times when carpenter ants are found within a structure, they are likely to have infested after termites have already damaged the wood.

Carpenter Ant Habitat

Often, nearby sources of decaying wood will give carpenter ants a perfect place to nest. Fence posts, logs, landscaping timbers and tree stumps and decaying limbs are all places you might find carpenter ant destruction. Even stumps which have been ground to sink below the soil will become infested as well. Depending on the circumstances, it may not take long before they make their way into your structure where their destructiveness might go unnoticed for years.

Carpenter ants are primarily an outdoor insect infesting wood within the natural environment

Carpenter ants live primarily within the outdoors and nest in a variety of woods including hollow logs like this one.

Log and wood-sided homes are most at risk. Exposed wood can contain decaying and rotting areas which may go unnoticed to you and I, but not to carpenter ants. Homes that contain lots of exposed wood inside can also be at risk. Any home that leaks and allows wood-members to absorb moisture can be at high risk for carpenter ant infestation. Furthermore, homes with high humidity levels may also be at risk.

Once carpenter ants become an indoor pest, they can do significant damage to wood and other building materials.

Carpenter ants can damage more than just wood. They have rendered this insulation useless, since they have excavated around the edges.

Gaps, cracks and holes will provide an entry point for any pest, including carpenter ants. Sometimes, they use electric lines and tree branches to enter areas high above our view point. This means they can begin to do damage up high where you may never notice.

Carpenter Ant Damage

Carpenter ants may not do quite the damage termites will but they are a destructive pest nonetheless. As previously stated, they often enter and attack areas where we do not frequently come in contact. These areas include crawlspaces, attics, within wall voids and more. In my 20+ years in this industry, I have personally observed carpenter ants in a variety of homes and various locations within the home.



One of the first instances of carpenter ants I observed was an infestation within dry cabinetry inside a local mobile home. Their damage wasn’t extensive but was well underway. It’s unclear if any damage to wall studs and other hidden wood was present. We performed a carpenter ant treatment on the structure and eliminated the problem. Several years later, the problem returned to the same area, which required a second treatment and replacement of the cabinetry.


In this inspection, we discovered carpenter ants trailing the wiring inside a mobile home in Monticello, KY. They were constantly being found around outlet and switch plates throughout the home. Upon inspection, it was found that a huge colony was living within the crawlspace and accessing the home through the main electric source. From there, they were traveling throughout the home and causing damage on almost every wall in the structure. A baiting program was implemented and 6 months later the infestation was gone. However, the damages remained and were to cost thousands in repairs.


A brand new home was found to be infested with carpenter ants in the crawlspace and we received the call for an inspection. The land had been cleared of timber and a home built upon the property immediately after. The observable colony measured approximately three square feet and consisted of thousands of carpenter ants. Minimal damage had occurred to this 6 month old home. We performed a treatment and eliminated the issue. We are unsure if the problem returned at a later date.


In this particular case, we observed a carpenter ant colony infesting a 1 foot square area of water-damaged wood at an electric weather head boot on a local homeowner’s roof. Luckily, the homeowner caught it shortly after their initial infestation. Unfortunately, they were excavating termite damage that was already present. Termites were found in several places and both a termite and carpenter ant treatment were necessary. We performed both treatments and the homeowner had the roof area repaired. However, if it weren’t for the fact that they were remodeling the home, these ants could have gone on to do significant damage without being seen,


This case of carpenter ants was presented to our company  as an infestation in an attic area which had no human accessibility. They were being found in light fixtures throughout the home and were beginning to be seen on the walls and floors. This particular home had a metal roof and was later found to have been poorly installed over an old shingle roof which was severely damaged. Carpenter ants were working through the shingles and accessing the damp wood. Treatment took around 2 years of baiting applications to eliminate the problem. Multiple colonies were present and the home was surrounded by woods with trees touching the home all around. Severe damage was present and repairs were costly.


We received this call regarding carpenter ants in a local home on a wooded lot. The ants were scattered throughout the home and would appear a few at a time very randomly and sporadic. When we arrived on the scene to perform inspection, it was discovered that extensive termite damages were present throughout the home and were still active in several places. What was most notable, however, was that carpenter ants had claimed several damage sites and were excavating and colonizing them causing further damage to the structure. Both a termite treatment and carpenter ant treatment were required. Each year, we return to treat carpenter ants outside the structure on this wooded lot.

What’s All This Mean?

Simply put, carpenter ants are destructive and can certainly damage a structure, even going unnoticed for years. Additionally, the presence of carpenter ants likely indicates an underlying problem with moisture. Where there is moisture in contact with wood, there are also likely termites. So if you see the presence of carpenter ants inside your home, you need a thorough inspection!

It’s worth noting that carpenter ants might prefer damp wood, but just like you and I, they can deviate from what they prefer. If your home has exposed wood, keep an eye on it. If you find any small holes or sawdust, call in some pros to investigate. You never know, it just might be carpenter ants!

How To Help Prevent the Destructive Carpenter Ant

To prevent carpenter ant infestations, here are a few rules to follow:

  • Keep limbs cut off the roof line and away from the structure. No trees or shrubs should be with 16 inches of the structure at any point.
  • Monitor exposed wood for soft or weak spots and repair as needed.
  • Keep exposed wood treated against the elements with your preferred protectant.
  • Remove any dead and decaying wood from around the structure.
  • Keep firewood 20 feet from the structure and at least 4 inches off the ground.
  • Monitor gutters and downspouts for proper operability. Repair as needed.
  • Watch for structural leaks in roofs, doors, windows and other areas, repairing as soon as found.
  • Keep an eye out for leaky plumbing and fixtures and have those repaired right away.

These are only a few tips to avoid carpenter ant infestation. Always be aware that wet or damp wood, leaks and unwanted water are always conducive to pests. Dry homes are less likely to be inhabited by pests. Proper moisture control on all fronts is ideal. Sealing all cracks, crevices and entry points is helpful as well.  Carpenter ants are destructive pests which require moisture to survive. Eliminating that moisture can help eliminate and prevent the pest.