Traverse City Record-Eagle


Carpenter ants invade!

By Erin ParkerA common and pesky pest problem in northern Michigan homes occurs when carpenter ants decide to sneak inside your house or outbuildings and take up residence.  Ants are social little critters, and if they aren’t controlled quickly, they soon establish colonies in concealed spaces, munching out tunnels and cozy nest chambers inside your home’s wooden framework, including: beams, posts, floor joists, sill plates, wall studs, etc.  Over time, the ants will weaken or even destroy the structural integrity of your house.

Carpenter ants are much larger than most other ants, about ½” long, and are usually black. They’re especially active in the spring and early summer months when swarms of a winged version of the ants emerge and start flying around.  These winged ants are the reproductive colonizers and they’re out actively looking for locations to start new nests.

Since most homes around here are built using wood, if you’ve been noticing carpenter ants around your house, it could be sign for concern.

Don’t get too worried if you see just a few big ants,  even a couple winged ants, running around inside your house – this doesn’t necessarily mean that you have a problem.  The ants could just be scouts out looking for food or, in the case of winged ants, ants that flew in an open door and been trapped inside.

However, if you’ve noticed lots of carpenter ants inside, especially, if you’ve seen more than a few swarming winged carpenter ants, there’s a good chance you have an infestation.

Carpenter Ants or Termites?

Although they share similarities, carpenter ants and termites aren’t the same.  Termites are more destructive and, fortunately for us, they’re relatively rare in northern Michigan – they’re more common further south.  Termites are worse because they actually consume wood – it’s their main food source.  Carpenter ants on the other hand don’t eat the wood.  They just chew out tunnels and large cavities inside of wood in order to create a cozy place to live and raise new generations of ants.

With carpenter ants, the cavities in the damaged wood are clean (except for eggs and ants) and the wood is smooth.  If the damaged wood is ragged and riddled with layers of packed dirt, I hate to tell you this, but you’re probably dealing with a termite problem.

Where do they come from?

In nature, carpenter ants make their nests in dying or dead trees, tree roots, stumps, or in pieces of wood lying directly on the ground.  They come out of their wood homes mostly at night to forage for food and to scout for new satellite locations for their colony.

Why do they come inside?

Unfortunately, carpenter ants are also perfectly happy to nest in any moist wood that they find inside of buildings, especially in areas in or near the woods (i.e., northern Michigan).  They like damp or humid crawl spaces, or anywhere else where there is a source of water from roof or plumbing leaks, condensation, or poor air circulation.

Besides crawl spaces or damp basements, carpenter ant nests are often found under or behind bathroom tiles; around bathtubs, sinks, showers, dishwashers and washing machines; under leaking roofs, around masonry chimneys, behind leaking or missing flashings, under poorly caulked or damaged exterior siding (especially cedar or plywood siding), or in rim joists or sill plates that are too close to grade, or in contact with mulch or shrubbery.

Once they get fully established, they’ll sometimes run out of space in the damp wood and start expanding satellite colonies into other dryer areas of the house framing.

Prevention and Treatment

To prevent carpenter ants from setting up nests inside your house, make sure to look for and eliminate sources of moisture.  Aside from causing other serious problems like toxic mold and rot, moisture attracts ants like a magnet and is the key to their survival.  Make sure that your crawl space or basement is well ventilated.  Fix leaks and damp conditions inside the house right away and replace any moisture-damaged wood that you find.

Outside, remove stumps, roots and old wood posts near the foundation.  Prune branches, especially dead branches overhanging or near the structure.  Also, prune any branches that touch electrical lines or other utility wires connected to the house.  Aside from protecting the wires from storm damage, carpenter ants often travel from branches to wires and use them like a highway to get into buildings.

Look for and seal any cracks or leaks you find in the foundation.  Make sure all your flashings, caulking and weatherseals are in good shape– this will also sav on energy costs.  Firewood or lumber stored in the garage or near the house should be kept dry and, if possible, elevated to allow air circulation.

If your house is already infested by carpenter ants, don’t despair.  With a little detective work these ants can be usually be successfully located and eradicated.

The first step is to find out exactly where their nests and tunnels are located.  This can be pretty tricky, since these nests are almost always hidden in difficult to reach or totally concealed spaces.  Often times, finding the nests involves carefully watching the ants to see from where they are coming and going.  Look for trails where they come in and out of their hiding places and small piles of sawdust.  Use a flashlight and look around in the crawl space or basement and up in the attic. Also look inside plumbing access panels and in, under and behind bathroom (moisture) and kitchen (food) cabinets.  Since it’s common for carpenter ants to travel inside walls, floors and ceiling spaces along electrical wires, one way to find them is to remove outlet and switch covers and take a look inside – just be careful not to shock yourself.

Once the nesting locations are located and exposed, they can be treated directly using any of the various types of ant-specific pesticides available at the hardware store.  As an added precaution, also treat the perimeter of the foundation and spray liberally under the edges of siding and trim, around window and door frames, and on any exterior carpenter ant trails you have located.  Remember to read and follow all safety precautions so you don’t make yourself sick.

Please note: if you find you have an advanced infestation of carpenter ants, with multiple nesting sites and damage, or if you suspect that you have a termite infestation, you should consider seeking help from a professional exterminator.

One last note: carpenter ants have their place and are one of Mother Nature’s many ways of decomposing dead wood.  If you notice these ants outdoors doing their job and they don’t seem to be invading your home, don’t’ be in too big a rush to poison them.  I say live and let live…

I hope this information proves useful. If you have questions about this or any other topic, please feel free to contact me at  I’ll try my best to point you in the right direction…

  • Mackinacjack

    This was so informative…we need this kind of info…thanks!  I’ve notice a lot of ants on the deck and will be looking at them now with a different “eye”.  Thanks and we look forward to more of yur blogs.

  • Brian

    Very informative.  Ha d a few of the flying variety in my kitchen a couple of weeks ago.  Nothing since.  Now I understand what they are and why they were there.

  • Randy Man

    You didn’t mention that if you see the ants only in the spring / summer, they are probably not nesting in your house. a little night time flashlight work is in order. I finally found mine coming in under the front porch. I put in my time looking,too. If you can’t find them do this: mix one part ground up dog food (dry) or canned (preferred) with two parts jelly, the cheaper the better. Don’t be a rocket scientist here, and about 1 1/2 cups will do. Place it in a jar lid or two by the wall nearest to where you have seen the most ants. After you see them eating this, mix a little boric acid, available at any drug store, to the tune of 1 tablespoon to 1 cup food. The workers will take the food back to the nest and the rest of the colony will feast on it. When that happens, it will kill the whole colony. This much of a mixture will not harm humans or animals, but keep it out of their reach anyway. And like my Grandpa always said,” It’s not gettin ‘em thats bad, it’s keepin ‘em that is “. Wise words for a a lot of things. Good luck it’s not the end of the world.

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