Termites are social insects that break down wood and other cellulose material. While there are over 2,700 recognized species globally, only a handful of major groups cause structural damage that concerns homeowners. Most destructive termites fall into three primary categories based on their habitat and moisture needs. Understanding these classifications is the first step in protecting property.
The Primary Classification Groups
Termite classifications are primarily defined by the amount of moisture they require to survive and where they establish their colonies. The most common and damaging group is the subterranean termite, which requires constant contact with soil or a consistent moisture source. These termites build the largest colonies of any insect in the United States, and they are responsible for the majority of structural damage across the country. They cannot survive exposure to open air and must maintain a connection to the damp earth.
Drywood termites, in contrast, do not require any contact with the soil to establish a colony. They are able to live entirely within the wood they consume, extracting all the necessary moisture from the cellulose through digestion. Found most often in warmer coastal and southern regions, these colonies are generally smaller than their subterranean counterparts and cause damage at a slower, but still significant, rate. They enter structures through exposed wood or through items like infested furniture brought into a home.
The third main classification is the dampwood termite, which requires wood that is already high in moisture content or decaying. These termites are often found in:
- Fallen logs or stumps.
- Structural wood suffering from plumbing leaks.
- Poor ventilation areas.
- Drainage issues.
Since they rely heavily on water damage, they are less likely to infest sound, dry lumber but their presence is a clear indicator of a significant moisture problem in the structure. Dampwood termites are also noticeably larger than the other two main types.
Identifying Features and Habitat Differences
The signs of an infestation vary significantly between the three main termite groups, reflecting their distinct living habits. Subterranean termites rely on mud tubes, which are tunnels made of soil and wood particles constructed to travel from the soil to the wood without exposure to the air. Their feeding often follows the grain of the wood, resulting in galleries that are packed with a mixture of soil and feces. When they swarm, the reproductives have dark bodies and two pairs of translucent wings that are nearly twice the length of their body.
Drywood termites leave behind the most distinct physical evidence in the form of frass, their fecal pellets. These pellets are expelled from the galleries through small “kick-out” holes and resemble tiny, six-sided, sand-like grains that collect in small mounds beneath the infested wood. Unlike subterranean swarmers, drywood swarmers often have a reddish-brown head and their wings feature three or more heavily pigmented veins. The damage they inflict involves creating smooth, clean galleries that cut across the wood grain, and they do not mix soil into their tunnels.
Dampwood termites typically do not produce mud tubes or piles of frass beneath the wood, as they often plug their entry holes with their own droppings to maintain high humidity within the galleries. The wood they infest is usually soft and decayed, and their galleries are generally large and open. Finding wood that sounds hollow or feels soft to the touch, especially near a consistent water source, can indicate the presence of this high-moisture species. Their swarmers are the largest of the three types and have a yellowish-brown body.
The Social Structure of the Termite Colony
All termite colonies operate using a caste system.
The worker caste makes up the largest population and consists of soft-bodied, pale, wingless individuals. Workers are responsible for all the labor, including foraging for food, feeding the other castes, and constructing and repairing the nest tunnels. These are the termites that consume the wood and cause the structural damage.
The soldier caste is slightly larger than the workers and is easily identifiable by its large, often brownish head and powerful mandibles. Soldiers are sterile males and females whose only function is to defend the colony against predators, primarily ants, especially when a tunnel or nest is breached. They form a defensive line to protect the workers and reproductives.
The reproductive caste includes the winged swarmers, or alates. These alates leave the nest to mate and establish new colonies, becoming the primary reproductives—the king and queen. The queen’s primary role is egg-laying, while the king stays with her to ensure continued reproduction; pheromones produced by the primary reproductives help regulate the development of other castes within the colony.