The simple answer is that carpenter ants do not eat wood; they only excavate it. Unlike termites, which possess specialized gut microorganisms to digest cellulose for nutrition, carpenter ants lack the necessary biological mechanism to derive sustenance from wood. Their tunneling activity can compromise the integrity of wooden structures, making the distinction between consumption and excavation important for effective pest management.
The Critical Distinction: Excavation Versus Consumption
Carpenter ants tunnel into wood solely to create nesting sites, known as galleries, which provide shelter for the colony and a protected environment for raising their young. They use their powerful mandibles to chew away wood fibers, creating smooth, clean tunnels within the material. This process is purely mechanical, and the removed wood material is simply discarded from the nest rather than being ingested. These insects are primarily attracted to wood that is already softened by moisture, decay, or fungal growth, as this material is easier for them to excavate. Outdoor parent colonies often establish themselves in dead trees, tree stumps, or decaying logs.
What Carpenter Ants Actually Eat
Since wood is not a food source, carpenter ants rely on an omnivorous diet of proteins and sugars to sustain their colony. Outdoors, a primary source of sugar is honeydew, a sweet liquid excreted by aphids and scale insects, which the ants actively collect. They also forage for protein by consuming other living and dead insects, which is essential for larval development. When foraging indoors, these ants seek out similar nutritional sources, readily consuming sweet items like syrups, honey, and fruit juices. They will also take advantage of household proteins, including meat scraps, grease, and pet food left in bowls.
Signs of Infestation in Trees and Structures
The most definitive physical sign of a carpenter ant infestation is the presence of “frass,” a material consisting of fine sawdust mixed with dead insect parts and other refuse. This debris is pushed out of the nest through small “kick-out” holes and often accumulates in conical piles below the infested area. The appearance of the galleries themselves is also a strong indicator, as the tunnels are notably smooth and polished, unlike the rough, mud-lined tunnels created by subterranean termites. In trees, frass may be visible near the base or in bark crevices. Secondary signs of an active infestation include subtle rustling sounds that can sometimes be heard within walls. The sighting of large, black worker ants foraging indoors, or the emergence of winged reproductive ants (swarmers) from hidden crevices, strongly suggests a well-established colony nearby.
Managing Carpenter Ant Activity
Effective management begins with identifying and eliminating conditions that attract these pests, especially sources of excess moisture. Carpenter ants need a constant water source, and wood softened by leaks, poor ventilation, or drainage issues is a prime target for nest establishment. Promptly repairing leaky pipes, ensuring gutters are clear, and increasing ventilation in damp areas reduces the likelihood of infestation. The mitigation strategy must focus on locating and treating the main nest and any satellite colonies. Trimming back tree branches or shrubs that touch the structure also prevents ants from easily gaining access to the building.