Red carpenter ants are large ants with reddish coloring on their head and thorax and a black abdomen. The most common species in North America is sometimes called the red and black carpenter ant, and like its all-black relatives, it excavates wood to build nests, potentially causing structural damage to homes over time. They don’t eat wood the way termites do. Instead, they chew through it with powerful jaws and push the debris out, leaving behind smooth, clean tunnels.
How to Identify Red Carpenter Ants
Red carpenter ants are slightly smaller than the common black carpenter ant but still large for an ant, typically ranging from a quarter inch to over half an inch long. The most recognizable feature is the color split: the head and midsection (thorax) are reddish-brown, while the abdomen is black. Like all carpenter ants, they have a single node (a small bump) between the thorax and abdomen, an evenly rounded thorax profile, and elbowed antennae.
These details matter because red carpenter ants are often confused with other species. Fire ants are much smaller and build soil mounds rather than nesting in wood. Termites, which cause similar wood damage, look quite different up close. Termites have straight antennae, wings of equal length, and bodies that are the same width throughout. Carpenter ants have a distinctly pinched waist, elbowed antennae, and winged individuals have front wings noticeably longer than the back pair.
Where They Nest
Red carpenter ants need moisture to establish a colony. The parent colony, where the queen lives and lays eggs, is almost always located somewhere with a steady supply of dampness: a tree stump, a rotting log, a standing dead tree, or a planter box. The queen never leaves this main nest.
The problem for homeowners starts when the colony grows large enough to establish satellite nests. These secondary colonies, made up of workers, larvae, and pupae but never eggs, frequently end up indoors. Common indoor locations include wall voids, attic spaces, insulation, hollow doors, window and door casings, voids beneath kitchen or bathroom cabinets, and hollow decorative beams. Once a satellite colony is established inside structural wood, the workers may expand into nearby lumber, gradually hollowing it out.
A carpenter ant problem that goes unnoticed can lead to significant structural damage. The damage accumulates slowly, often over years, but because the galleries weaken load-bearing wood from the inside, the consequences can be serious by the time they’re discovered.
Signs of an Infestation
The most telling sign is frass, a sawdust-like material that collects beneath baseboards, windowsills, or behind appliances. It’s easy to sweep up and forget about, but if it keeps reappearing, that’s a strong indicator. Carpenter ants push this debris out of their tunnels as they expand, and the material is usually a mix of chewed wood shavings, soil particles, and insect parts. Unlike termite droppings, which look like tiny pellets, carpenter ant frass resembles coarse, fibrous sawdust.
In a quiet house, you might also hear faint rustling inside walls. It’s subtle, but the sound comes from hundreds of ants moving through their galleries. If you tap on wood and it sounds unexpectedly hollow, that’s another clue. The tunnels carpenter ants create are distinctively smooth and clean inside, giving damaged wood a hollowed-out feel even when the surface looks intact.
Seeing large winged ants indoors, especially in spring or early summer, is one of the clearest red flags. These are reproductive ants (queens and males) preparing for mating flights, and their presence inside usually means a mature colony is living somewhere in the structure. Swarming is triggered by warm, humid, calm weather, typically in July or August for many species, though the exact timing varies.
What They Eat
Carpenter ants have a varied diet, which is part of what makes them successful and also part of what makes baiting them tricky. They feed on honeydew produced by aphids and other plant-sucking insects, dead insects, and sweet or protein-rich foods found in homes. They forage mostly at night, sometimes traveling considerable distances between their outdoor parent colony and indoor satellite nests. Watching their trails after dark is one of the best ways to trace them back to a nest.
Colony Structure and Life Cycle
A carpenter ant colony operates on a caste system. The queen’s sole job is laying eggs. Female workers handle everything else: caring for eggs and larvae, foraging, defending the colony, and excavating new galleries. A mature colony may contain thousands of workers spread across the parent nest and multiple satellite colonies. When the colony reaches a certain size and maturity, the queen begins producing winged virgin queens (sometimes called princesses) and winged males (drones). These emerge during warm, humid weather for a nuptial flight, scatter, mate in the air, and the newly mated queens land to start colonies of their own.
New colonies grow slowly at first. It can take several years before a colony is large enough to produce satellite nests or cause noticeable damage. Carpenter ant queens can live for over a decade, which means an untreated colony will continue growing and expanding into new wood for years.
How to Get Rid of Red Carpenter Ants
The most important step is finding and eliminating the nests, both the parent colony and any satellites. Destroying one nest while others remain untouched won’t solve the problem. Follow foraging ants at night with a flashlight to trace their trails. Look for cone-shaped piles of frass near nest entrance holes. A moisture meter can help locate damp areas inside walls where nests are likely hiding.
Because carpenter ants eat such a wide range of foods, baits are less consistently effective than they are for other ant species. However, liquid sugar baits made with a low concentration of boric acid (0.5 to 1%) can work. Higher concentrations are actually less effective because they become repellent. A simple homemade version is half a teaspoon of powdered boric acid and nine teaspoons of sugar dissolved in one cup of hot water. Place bait stations near trails and nest entrances, ideally starting in late winter or early spring when colony populations are at their lowest.
For nests located inside wall voids, dust insecticides are the preferred option. Products containing boric acid, silica gel, or diatomaceous earth can be applied directly into the void. Liquid insecticides should never be sprayed into wall cavities, as the water can damage insulation, drywall, and electrical wiring. Non-repellent dust formulations tend to work better because ants walk through the material and carry it deeper into the colony rather than avoiding treated areas.
Preventing Reinfestation
Moisture is the single biggest factor that attracts carpenter ants. Fix leaky roofs, windows, door frames, and plumbing. Replace any wood that has been previously damaged by ants, termites, rot, or water. Paint or seal exposed wood before it gets wet. Eliminate any direct contact between soil and wooden parts of your home’s structure.
Trim trees and bushes so no branches touch the house, since carpenter ants use these as bridges. Remove dead stumps, fallen logs, and old firewood stacked near the foundation. These serve as ideal parent colony sites, and once a colony matures nearby, your home becomes a natural target for satellite nests. Keeping a clear, dry perimeter around your house is the most reliable long-term defense against red carpenter ants and their relatives.