Carpenter ants are common household pests recognized for their large size and the extensive damage they can inflict upon wooden structures. This reputation often leads people to believe that these ants eat the wood, similar to termites. The truth about how these insects interact with timber is frequently misunderstood, creating a major misconception about their behavior. Understanding the fundamental difference in their activity is the first step in properly identifying and managing a carpenter ant issue.
The Critical Distinction: Excavation vs. Consumption
Carpenter ants cannot digest cellulose, the primary component of wood. Unlike termites, which break down wood fibers for nutrition, carpenter ants use their strong mandibles solely for mechanical excavation to create nesting sites. This distinction is important because it changes how the damage appears. They chew through the material, creating a system of tunnels and chambers called galleries to house the colony, eggs, larvae, and the queen. Carpenter ant galleries are characteristically clean and smooth, often described as having a sandpapered look. Termite damage, in contrast, typically features galleries packed with mud or fecal pellets. Their tunneling activity can still compromise the structural integrity of a building over time, especially when large colonies are involved.
The True Diet of Carpenter Ants
Carpenter ants are omnivores, relying on a varied diet of proteins and sugars for their nutritional needs. Proteins are important for developing larvae and the queen during the egg-laying season in spring and early summer. The ants primarily acquire protein by foraging for other insects, both living and dead, which can include flies, caterpillars, and even termites. Adult workers require simple carbohydrates and sugars for energy, often sourced naturally from honeydew excreted by aphids and scale insects. When indoors, they readily consume household items such as fruit juices, syrups, jelly, pet food, meat scraps, and grease.
Identifying Signs of Carpenter Ant Damage
A reliable indicator of an infestation is the presence of “frass,” the material ejected from the nest during excavation. Frass consists of coarse wood shavings, resembling the output from a pencil sharpener, often mixed with debris like dead insect parts, soil, and pupal cocoons. This material is pushed out through small openings in the wood surface called “kick-out holes.” These holes are typically only a few millimeters in diameter and are often found near baseboards, window frames, or door casings. Another sign is the sound of the ants moving or chewing inside the wood, sometimes heard as a faint rustling or tapping noise in quiet areas. If a section of wood is tapped and sounds hollow, it may indicate that the material has been excavated from the inside.
Primary Nesting Habitats
Carpenter ants prefer nesting in wood softened by moisture, fungal decay, or previous damage, as this material is easier to excavate. Sources of water leaks, such as poorly sealed windows, leaky roofs, and plumbing fixtures, are common attractants. The presence of these ants often signals an existing moisture problem within the structure that needs to be addressed. A large colony establishes a “parent colony,” which typically contains the queen, eggs, and many workers, usually located outdoors in a dead tree, stump, or firewood pile. As the colony grows, it may create “satellite nests” indoors, housing workers, larvae, and pupae, but not the queen. These satellite nests are connected to the main colony by foraging trails and are a major cause of structural damage.