Ants are often found in wood, leading to the common assumption that they consume it, similar to termites. This is a misconception; ants are attracted to wood primarily for shelter and nesting sites, not as a food source. They excavate tunnels and galleries to create suitable habitats for their colonies, a behavior that sets them apart from wood-eating insects.
Why Ants Seek Wood
Ants are drawn to wood because it provides an ideal environment for constructing their nests. They do not digest wood; instead, they excavate it, using their strong mandibles to create tunnels and chambers. This excavation process produces sawdust-like debris, which the ants then remove from their galleries.
These insects prefer wood that is already compromised, such as soft, damp, or decaying timber. Wood with a moisture content greater than 15 percent is particularly appealing for establishing a parent nest, which houses the queen, eggs, and small larvae. Existing structural damage or moisture issues, often caused by leaks or condensation, make the wood easier to tunnel through and thus more attractive for ant colonization. While parent nests require moisture, satellite nests, containing larger larvae and pupae, can exist in drier wood.
Key Wood-Dwelling Ant Species
The primary ant species known for inhabiting wood is the carpenter ant, belonging to the genus Camponotus. These ants are among the largest in the United States, with workers typically 1/4 to 1/2 inch long, and queens up to 1 inch. They are commonly black, or sometimes bicolored red and black, and possess a distinct evenly rounded, arched thorax when viewed from the side, along with a single node between the thorax and abdomen.
Carpenter ants excavate extensive galleries within wood to establish their nests, often in dead or decaying wood, or in building materials softened by moisture. They do not consume the wood but rather remove it to create living spaces. While carpenter ants are the most prominent wood-dwelling ants, other species, such as some pavement ants or odorous house ants, might occasionally nest in damp wooden environments.
Identifying Ant Activity in Wood
Identifying ant activity in wood involves observing specific signs that differentiate it from other wood-destroying organisms. One primary indicator is the presence of smooth, clean galleries within the wood. Unlike the rough, mud-lined tunnels created by subterranean termites, carpenter ant galleries appear sanded and free of debris.
Another sign is the presence of “frass,” which is a mixture of sawdust-like wood shavings, insect parts, and sometimes ant fecal matter, soil, or gravel. Carpenter ants expel this frass from small “kick-out” holes in the wood, often resulting in small piles accumulating beneath these openings. Live ants, particularly large black ones, seen foraging or emerging from crevices, can signal an infestation. Faint rustling or scratching sounds emanating from within walls or wooden structures, especially at night when carpenter ants are most active, indicate their presence. These signs are commonly found in areas susceptible to moisture, such as door frames, window sills, and structural timbers.
Distinguishing Ants from Termites
Differentiating between ants and termites is important due to their distinct biological characteristics and the varying types of damage they inflict. Physically, carpenter ants have a constricted, narrow waist, elbowed (bent) antennae, and, if winged, their hind wings are shorter than their front wings. Termites, in contrast, possess a broad waist, straight, bead-like antennae, and their four wings are typically uniform in size and length. Termite swarmers also often shed their wings easily.
The damage they cause also differs significantly. Carpenter ants excavate wood to create smooth, clean galleries for nesting, leaving behind a sanded appearance; they do not consume the wood. Termites, however, actively eat wood, creating tunnels that are often rough, ragged, and may be lined with mud or soil. Subterranean termites construct distinctive mud tubes on surfaces as protected pathways between their underground colonies and food sources. The frass, or droppings, from each insect also varies: carpenter ant frass resembles sawdust mixed with insect parts, while drywood termite frass consists of small, uniform, pellet-shaped fecal pellets.