Termites are highly social insects, and the visual evidence of their presence varies dramatically depending on the species. The structures homeowners encounter are typically not the central colony itself but rather the pathways or discarded materials left behind by foraging insects. Termite evidence falls into two distinct categories: the earthen tunnels of subterranean species and the wood-based droppings of drywood types.
The Appearance of Subterranean Structures
The most common visual sign of subterranean species, such as Reticulitermes, is the presence of mud tubes, also known as shelter tubes. These earth-colored pathways are built by worker termites using a mixture of soil, wood particles, and saliva or feces. The tubes provide a sheltered, high-humidity environment, protecting the insects from predators and dry air.
Working tubes, the main thoroughfares for the colony, are typically about the width of a pencil, ranging from one-quarter to one inch in diameter. They are frequently found along concrete foundations, climbing walls, or traversing floor joists, acting as highways between the underground nest and the wood food source. Other types, like exploratory tubes, are thinner and more fragile, extending outward in search of new wood before being abandoned.
The main nest of a subterranean colony, often referred to as carton material, is located either underground or within a structure where a reliable moisture source is present. This central colony is generally not visible to the homeowner because it is excavated deep beneath the foundation or hidden within wall voids. Finding a mud tube on an exposed surface is the clearest indication that the unseen colony is actively foraging nearby.
Identifying Drywood Termite Evidence
Drywood termites establish their entire colony directly within the wood they consume and do not require contact with the ground. Because they live entirely within the wood, they do not construct mud tubes, making their evidence less conspicuous than that of subterranean species. The primary sign of their activity is the accumulation of fecal pellets, known scientifically as frass.
This frass is expelled from the wood through tiny “kick-out” holes that the termites create to clean their galleries. The pellets are small, dense, and uniform in size, measuring approximately one millimeter in length. Each pellet has a unique hexagonal or six-sided shape with concave sides, resembling fine, hard grains of sand or tiny pepper flakes.
The color of the frass can vary significantly, ranging from light tan to nearly black, depending on the type of wood the colony is consuming. Homeowners often discover small, cone-shaped piles of these pellets accumulating on horizontal surfaces directly beneath the infested wood, such as on window sills or floors. Less noticeable signs of internal damage include blistered or bubbling paint on wood surfaces, indicating that the insects are tunneling just beneath the surface.
Distinguishing Termite Nests from Ant Activity
Distinguishing termite evidence from the activity of other wood-damaging insects, particularly carpenter ants, is a frequent source of confusion. A comparative inspection of the debris and internal damage provides definitive visual clues. The most significant difference lies in the material found beneath the damaged wood: termites leave behind fecal pellets, while carpenter ants produce sawdust.
Carpenter ants excavate wood to create smooth, clean galleries for nesting, but they do not consume the wood itself; they simply push the resulting wood shavings out of the nest. This debris, or “ant frass,” is a fibrous, sawdust-like material, often mixed with dead insect parts and bits of insulation. Termite galleries, in contrast, appear rough and are often coated with a layer of mud or fecal material.
Inspecting the appearance of winged reproductive insects, or swarmers, also offers a clear distinction. Termite swarmers possess four wings that are nearly equal in size and significantly longer than their body, and they shed these wings easily after swarming, leaving small piles of discarded wings behind. Carpenter ant swarmers have hind wings that are noticeably shorter than their front wings, and they retain their wings after a mating flight.