Carpenter ants do not eat wood. Unlike termites, they can’t digest cellulose, the tough fiber that makes up wood. Instead, carpenter ants chew through wood to carve out nesting galleries, then push the debris out. The wood has no nutritional value for them whatsoever.
What Carpenter Ants Actually Eat
Carpenter ants are foragers with a sweet tooth. Their primary food source is honeydew, a sugar-rich liquid excreted by aphids and scale insects feeding on tree sap. Carpenter ants feed mainly in the tops of trees, where they consume honeydew directly from these insects throughout the spring and summer. It’s a reliable, abundant energy source, and many ant species depend on it.
Beyond honeydew, carpenter ants eat other insects (both living and dead), fruit, and protein-rich scraps. Indoors, they’re drawn to sugary foods, grease, and meat. If you examine debris near a nest closely, you’ll often find discarded parts of prey insects the ants brought back as food.
Why They Tunnel Through Wood
Carpenter ants excavate wood purely to build their homes. They chew out smooth, clean galleries that run parallel to the wood grain, starting with the softer layers of each annual ring and boring through the harder layers to connect tunnels. The result is a polished, almost sanded-looking interior, very different from the rough, mud-filled tunnels termites leave behind.
They strongly prefer wood with a moisture content of 15% or higher, which means a carpenter ant problem is almost always tied to a moisture problem. Outdoors, they nest in tree stumps, dead trees, logs, and tree holes. Indoors, they target areas where wood stays damp: near leaky windows, doors, roofs, and plumbing. Wall voids, attic areas, hollow doors, window casings, and the spaces beneath kitchen and bathroom cabinets are all common indoor nesting sites.
How to Spot the Damage
Because carpenter ants push excavated material out of their tunnels rather than consuming it, the clearest sign of an infestation is frass: small piles of wood shavings mixed with insect parts and soil. You’ll find frass in crawl spaces, basement areas, on window sills, along decks, or stuck to walls just below small “kickout holes” the ants use as exits. The shavings are soft and fibrous, loosely packed. That’s a key distinction from drywood termite droppings, which look like tiny uniform pellets resembling grains of salt or pepper.
The wood surface itself may look completely normal from the outside, or it may appear slightly sanded down. Tap on suspected areas and listen for a hollow sound. Other warning signs include seeing large black ants (roughly ⅝ of an inch, much bigger than the ⅛-inch pavement ants they’re sometimes confused with) wandering through your home, and finding winged ants on or near windows, which signals a mature colony nearby.
How Colonies Spread Inside a Home
Carpenter ant colonies have a layered structure that makes them tricky to eliminate. A mature colony splits into a main (parent) colony and one or more satellite colonies. The parent colony needs steady moisture, so it’s usually located outdoors in a tree stump or buried wood. Satellite colonies, which house workers, larvae, and pupae but never eggs, are the ones most likely to set up inside your walls. The queen always stays in the parent colony.
This means you can kill every ant you see indoors and still have the parent colony pumping out new workers from the yard. It also means that simply treating the visible nest may not solve the problem if you haven’t found the source.
Carpenter Ants vs. Termites
The confusion between these two pests is understandable since both are found in wood, but the damage they cause is fundamentally different. Termites actually consume cellulose as food and can severely compromise a home’s structural integrity. Termite repairs commonly cost upward of $3,000. Carpenter ant damage is more gradual, often taking years to become significant, with typical repair costs ranging from $250 to $500, though long-standing infestations can push that into the thousands.
A quick way to tell them apart: carpenter ant galleries are clean and smooth with visible wood shavings nearby, while termite tunnels are rougher and often contain soil or mud. Subterranean termites create a layered, hollowed-out pattern by targeting the softer wood first, and they use their own droppings as building material, so you won’t find pellets lying around. Drywood termites do leave droppings, but theirs are hard, uniform pellets, nothing like the fibrous sawdust carpenter ants produce.
Reducing the Risk
Since carpenter ants follow moisture, the most effective prevention is keeping wood dry. Fix leaky roofs, windows, and plumbing promptly. Replace water-damaged wood rather than painting over it. Keep firewood, tree stumps, and dead trees away from the house, and trim branches that touch the roof or siding, since carpenter ants use these as highways from their outdoor parent colony to potential indoor nesting sites.
Good ventilation in crawl spaces, attics, and basements also helps. If you spot frass or large black ants inside your home, trace their trail if you can. Workers forage along consistent paths between the nest and food sources, and following that trail is often the fastest way to locate the satellite colony inside your walls and the parent colony outside.