Carpenter ants closeup photo (C) Daniel Friedman Carpenter Ants
How to identify carpenter ants, inspect for ant infestation, structural damage prevention & cure

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Carpenter ant infestation photo guide:

This article describes carpenter ants and how to inspect a building for carpenter ant damage.

We explain and illustrate how to identify carpenter ants - what carpenter ants look like, why and where they attack buildings, and how to cure a carpenter ant infestation using pesticides or other methods.

We describe and include photographs of building details that increase the risk of carpenter ant attack - which tells you where to look for ant damage as well as how to prevent carpenter ant infestations in buildings without reliance on pesticides.

We also describe how to distinguish carpenter ants from termites and how to tell a carpenter ant from other ants. We include many photo-examples of building damage caused by carpenter ants. And we provide citations to authoritative sources for more carpenter ant identification & control information.

Our photo at page top illustrates a closer to actual size view of carpenter ants found during demolition in an area where the evidence of carpenter ant activity and damage justified tearing some building surfaces apart. .

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Carpenter Ants Guide

Winged ant (C) Daniel FriedmanWhat carpenter ants look like, how to find carpenter ant damage, how to get rid of carpenter ants, how to prevent carpenter ant infestations.

Carpenter ants (Camponotus pennsylvanicus) attacking a wood structure, if not discovered and evicted (or treated), can cause substantial structural damage to the building.

The black carpenter ant (Camponotus pennsylvanicus) is the most common carpenter ant member of the species found in wood structures in North America, though there are about 1000 members of the group.

[Click to enlarge any image]

Both black and red carpenter ants are found further north including some areas of Quebec.[4]

Carpenter ants may be winged (shown enlarged to about 5 x life size in our photo at left) if the colony is swarming, but more often you'll find them wingless.

Our wingless carpenter ant picture just below illustrates that carpenter ants might be baited to come out into the open with a bit of apple core.

Carpenter ants sampling an apple core (C) Daniel Friedman

Article Contents


Where to Look for Carpenter Ant Activity on buildings

Wood at ground and insect + rot damage Two Harbors MN (C) Daniel FriedmanHere are the principal approaches to inspecting a building for carpenter ant activity & damage:

These inspection points for finding carpenter ants and carpenter ant damage also tell us how to avoid their company: avoid wood in contact with or within 8" of soil, and fix and prevent water leaks into the building structure. Roof leaks, leaks at building flashing junctures of chimneys, leaks around windows and doors and into walls, and plumbing leaks in a building all make conditions inviting for carpenter ants.

Our first photo below provides an example of discovering carpenter ant frass right in the living area - in this case our client points out this "sawdust" on the light blue window window sill.

Often water leaks due to sealing or flashing areas around a window or door will send water into the wall, attracting wood destroying insects (WDI).

Carpenter Ant Damage (C) Daniel Friedman Carpenter Ant Damage (C) Daniel Friedman

Above, our second photo shows a significant amount of carpenter ant frass at a wood framing juncture. You might find carpenter ant frass on the floor below an area of damage like this before you look "up" to see the actual area of activity.

Carpenter Ant Damage (C) Daniel Friedman

The extensive structural damage to the wood floor in the building shown below occurred in a wood framed structure over an inaccessible crawl space in a New York cottage built in the 1920's along Wappingers Creek.

Wood framing was at ground level, in ground contact, and wet from roof leaks as well as surface runoff.

Carpenter Ant Damage (C) Daniel Friedman

We demolished the original structure (Willowbrook Hgts., Poughkeepsie NY), rebuilt the floor and sills using pressure-treated wood, we raised the foundation height to above ground level, and we corrected the water and leak problems.

Carpenter ant infestation can be higher in a building, even in the building roof.

Carpenter Ant Damage (C) Daniel FriedmanDon't restrict your carpenter ant inspection to ground level. Overhanging tree branches provide an easy path onto a building roof.

Leaks into a wood framed roof structure (often around a chimney) are an inviting condition for carpenter ants - they don't have to go downstairs to get a drink.

Our photo illustrates just how subtle a leak can be in a flat or low slope roofed structure.

That small area of ponding combined with improper type of drip edge (Gravel stop on an EPDM roof) directed water into the roof structure. That was enough invitation to start a carpenter ant colony.


Common roof leak areas such as around chimney flashing and at leaky eaves (or at areas of ice damming) are common sites for carpenter ant infestation.

Distinguish Between a Carpenter Ant and Swarming Termites

Carpenter ant sketch Termite identification sketch (C) Daniel Friedman

Our sketches show the difference in appearance between a winged carpenter ant (first image) and winged termite (swarming) (second image). [Click to enlarge any image]

Carpenter ants are about 1/2" long, are generally black, have long angled antennae, a segmented body, and a really narrow waist. Swarming carpenter ants have wings but otherwise they don't. The swarming carpenter ant's front wings are much longer than its back wings. Throughout this article you'll find more photos of both winged and wingless carpenter ants.

If your "flying ant" has an un-segmented body (second illustration above) it's probably a termite not a carpenter ant, and you should see TERMITE IDENTIFICATION & CONTROL.

Carpenter ants enjoying apple cores (C) Daniel Friedman

Our photo illustrates how easy it is to entice carpenter ants into the open if they are already nearby.

We left these apple cores on a kitchen cutting board in early spring - a time of peak carpenter ant exploring activity.

In less than an hour our local carpenter ants had found and were enjoying fresh apple juice.

Signs of Carpenter Ant Activity: Exploring Building Framing for Carpenter Ant Damage

Carpenter ant infestation evidence (C) Daniel FriedmanHere is a photo of carpenter ant frass or "sawdust" beneath an area of carpenter ant infestation in a building.

Unlike wood destroying termites, carpenter ants aren't "eating" the wood but rather tunneling through wood members to make space for their colony.

As a result, where there is fresh, current carpenter ant activity you will often find fresh, light colored sawdust (carpenter ant frass) below or at the area of entry or exit of the ant infestation.

Notice a second relevant clue to carpenter ant attack: the water stain on the plywood wall sheathing at the upper right corner of the photo. This stain and carpenter ant frass were found beneath a flat roof over a garage.

Without opening this wall and removing the insulation one would not be likely to see this carpenter ant colony nor any damage the ants are making to the structure until conditions were much more severe.

Below we illustrate further investigation of the carpenter ant attack whose clues were just above. At below left you can see much more compelling evidence of carpenter ant activity on the sill plate atop the same wall - a place no one might have looked without the first clue.

At below right you can see our disclosure of active carpenter ant activity and a sawdust trail (carpenter ant frass trail) that was located between the plywood roof deck and the wall top framing.

Carpenter ant infestation evidence (C) Daniel Friedman Carpenter ant infestation evidence (C) Daniel Friedman<

Signs of Carpenter Ant Activity: Exploring for Carpenter Ants at an Interior Wall at Floor Baseboard Trim

Our carpenter ant activity photos below illustrate the results of deciding to investigate further for ant activity and damage at the ground floor of a slab-on grade structure. After observing frequent carpenter ant traffic on the floor in this area we watched the ants to see where they seemed to be most busy (coming and going) at the wall bottom.

That led to a spot between two sliding exterior doors and an area where there had been some leakage into the wall cavity. Pulling off a small section of floor baseboard trim (below left) we found the main entry/exit point for our carpenter ants (below right).

Carpenter ant infestation evidence (C) Daniel Friedman Carpenter ant infestation evidence (C) Daniel Friedman

Probing into the wood post bottom in this location did not discover significant damage. We decided to address this carpenter ant problem by two simple DIY steps:

  1. We used a simple carpenter ant killing spray on the exposed surfaces inside and outside this immediate area combined with
  2. We repaired the exterior leak that was sending water into the wall at this post bottom.

Signs of Carpenter Ants: Frass or "sawdust" - Explore further for Carpenter Ants

Carpenter ant frass on indoor surfaces leads to further investigation (C)  RW

We’re wondering what these droppings could be that have been appearing for some time now and we just vacuum them up?

This is in a porch that is part of our house in Oakville, Ontario, but we tend to keep temperatures cooler say 50F during the winter. - Anonymous by private email 2018/04/09

Reply: fresh carpenter ant frass means find and fix the ant infestation

To me that looks like carpenter ant frass - a fancy word for the sawdust made when carpenter ants are ripping their way through wood in a structure. I'd do some careful probing and some inspection for leaks - it's often water in wood framed walls that invites ants into the structure.

Is there a basement below this area, or a crawl space where you could take a look? Or is this part of your home built on a slab.

Outside is there wood close to soil?

And as spring comes we might watch for swarming carpenter ants.

Don't panic. If we catch them in time we won't have to rebuild the porch - ok that's an editorial "we" as it's you and your porch but I didn't want you to feel abandoned.

Around Burlington, Oakville, and also Hamilton, Ontario carpenter ants are one of the more-common insect pests. I speculate that proximity to Lake Ontario moderates the climate a bit so we see more carpenter ants in southern Ontario than further north. I'd give a call to one of your local pest control companies.

Reader follow-up: here is what we found during exploration of the carpenter ant sawdust or wood frass

Carpenter ant frass on indoor surfaces leads to further investigation (C)  RW

The porch was more of an add- on with its own crawl space but its not really accessible as it only has an opening size of a couple cement blocks to get a heating duct out there.

However we should be able to shine a light out there from a crawl space under our house to see what’s going on. Theirs no wood outside just a concrete patio.

Above: on prying open the wood trim below a porch window, the carpenter ants ran amok.

Carpenter ant frass on indoor surfaces leads to further investigation (C)  RW

Above: access to the crawl area below this porch is very limited but where we could look we don't see obvious damage to the structure ... yet.

The porch sits on cement blocks however with a dirt floor. It has plastic sheet on the dirt similar to the larger crawl space under our addition that butts up to the porch.

Moderator follow-up:

That crawl space is a hard-to-access area. Look in there as much as you can for signs of so much ant damage that the sill bottom edges or sill plate top edge are crushing.

If you don't see such damage there and if you don't see signs of structural movement above the ant-infested area, then I'm doubtful that heroic demolition and repair would be justified.

Instead focus on

1. finding and fixing leaks into the crawl or into the wall cavity

2. have the area treated for carpenter ants - by a licensed PCO.

3. then vacuum up the ants (they hate that) and their frass in the finished area. That'll help you notice future activity.

Examples of Ants that are Not Carpenter Ants & that do not attack wood structures

NOT a Carpenter ant infestation evidence (C) Daniel Friedman

Here we illustrate ant activity that is not carpenter ants.

These little ants appeared within a few hours of our leaving a dead insect on a brick walkway.

These ants are not carpenter ants and are of no risk to the structure itself.

In addition to noticing where we found them (not attacking wood) one can observe that they are about 1/3 the size of a carpenter ant (shown at page top).

Below our first photo illustrates a large area free of grass and other plant growth - this is a large red ant colony typical of what one might find in the Southwestern U.S. or in Mexico.

This large ant colony was found along the edge of EL Charco del Ingenio in San Miguel de Allende, Guanajuato, Mexico.

Localizado a unos minutos de San Miguel de Allende, El Charco del Ingenio es un Jardín Botánico y una Reserva Natural extraordinaria. Posee una extensa colección de cactáceas y otras plantas suculentas de México, muchas de ellas raras, amenazadas o en peligro de extinción. -

These ants do not attack wood structures.

Watch out: these biting red ants are capable of a painful bite injecting a good dose of formic acid.

If you are hiking in an are where these ant colonies are found, don't stand idly around atop the ant colony or you'll find yourself invaded and attacked.

NOT a Carpenter ant infestation evidence (C) Daniel Friedman NOT a Carpenter ant infestation evidence (C) Daniel Friedman

Our second photo above provides a closeup of these people-biting ants.


Continue reading at TERMITE DAMAGE PROBING or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


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CARPENTER ANTS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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