By Walter Reins
ISA Certified Arborist®
August 22, 2024
Everyone loves to hate them, but did you know that carpenter ants are responsible for saving countless lives each year by dragging unsuspecting homeowners out of the way of falling limbs?
Okay, that’s completely false.
A carpenter ant!
While they may not be the most heroic Hymenopterans in the landscape, carpenter ants generally don’t deserve the “tree destroying, just-as-bad-as-termites” reputation they’ve gained over time. Like most people, places, or things that we think poorly of, there’s usually a good bit of misunderstanding or lack of knowledge that leads to false narratives. Let’s take a look at the habits of carpenter ants to understand them better.
You probably already know a few things about ants in general; they live in colonies, there’s usually one egg-producing female called the queen, they have a diverse diet that can include other insects, plant materials, sources of sugar in the landscape (berries, fruits, etc.) as well as human food. All of these traits apply to carpenter ants as well. But what makes carpenter ants different (among a few other things) is where they set up their nests, and this is an important fact to know if we are to better understand them. Carpenter ants will build nesting sites in moist, decaying wood. This could technically be in the structure of your home if you have an already compromised roof, flashing, or siding that has allowed moisture to decay the underlying framing. But most often these nests are in existing cavities of hardwood trees. If there is one important takeaway from this article, it’s this - carpenter ants DO NOT take perfectly sound, intact wood and turn it into decayed wood. If you see them, carpenter ants are simply an indication that decayed wood is already present, probably in a nearby hardwood tree. Think of it this way - if you sat your old collection of boy band CDs out to the curb, you might have groupies loitering in your front yard, but they’re probably not coming inside. The bigger concern in this case would be your neighbors finding out that you had a collection of boy band CDs in the first place. That’s right, you know who you are.
Carpenter ants on a freshly removed tree trunk with decayed wood present
Carpenter ants seeking out these existing pockets of decay in wood will further mine or carve out the area to create a hospitable and damp site to make new nests. You may see frass or shavings at the base of a tree that can indicate their mining activities within, even if you can’t see them on the outside of the tree. Worker ants that are busy foraging or scouting for new nesting sites can be spotted during the day, but are most active at night. The nesting sites do not contribute to faster decay of the area or further loss of structural integrity. If we should have an opinion about them that is anything other than neutral, let it be one of acceptance, perhaps even gratitude that these little creatures give us clues as to what’s happening in our trees.
One very common question about the cavities that can harbor these ants is “Can I cover it/fill it/seal it in some way to keep things out?” The answer is generally no. It’s virtually impossible to seal out oxygen and water from a cavity within the wood of a tree. And as long as there’s oxygen and moisture, unprotected/untreated wood will decay as nature intended it to. In fact, attempting to seal a cavity can often reduce (but not eliminate) airflow to the area, trapping moisture that would otherwise dry out during warmer, drier weather, and accelerating the rate of decay. The best approach for most trees is to assess their overall health and promote that health if the tree is deemed reasonably safe, or discuss and consider removal or major pruning if a whole tree or sections of it are determined to be hazardous.
Sawdust and a carpenter ant near a tree cavity.
One important distinction between carpenter ants and termites is that carpenter ants do not eat wood. If it is determined that you have a carpenter ant problem within the structure of your home, contacting a pest control company is perfectly acceptable - just remember that killing the ants doesn’t eliminate the underlying issue that attracted them in the first place. Although treating for carpenter ants in the landscape is typically not necessary, a pest control company would be required for that as well if you chose to have it done. As a professional tree care company that offers plant health care services, we are licensed to apply treatments to horticultural pests when needed. Since carpenter ants are technically categorized as wood-destroying insects, we cannot and do not treat for them at Russell Tree Experts.
To summarize, carpenter ants are probably less of an issue in your landscape than you think. If you have mature trees, you’re very likely going to see them around in the landscape. If you see a lot of them, it may indicate that a larger concern is present. Give us a call and one of our 20+ ISA Certified Arborists® can come out to inspect the trees on your property. If you’re simply not sure, remember that carpenter ants are largely nocturnal. So while you’re throwing out those CDs under the cover of darkness, take a flashlight with you and look around!
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Sincerely,
Walter Reins I Regional Manager, Russell Tree Experts
Walter became an ISA certified arborist in 2003 and has a degree in landscape horticulture. He has 25 years of experience in the tree and landscape industries and originally began working at Russell Tree Experts in 2011. Walter is also the owner/operator of Iwakura Japanese Gardens, a small design/build/maintenance firm specializing in Japanese-style gardens, and also offers responsible tree planting for all landscapes.