Drywood termites establish colonies directly within the wooden structures they consume, never needing contact with the ground or soil. These insects are common in southern coastal regions and can infest structural lumber, furniture, and hardwood floors. Because they live entirely inside the wood, evidence of their presence is often not obvious until an infestation is already established and significant. Detection can be challenging, as the termites themselves remain hidden, making it necessary to look for subtle signs of their activity.
Physical Appearance of Drywood Termite Castes
Drywood termite colonies are organized into a caste system, though they lack a true worker caste. The winged reproductives, known as alates or swarmers, are typically the most visible caste, measuring between 1/4 and 1/2 inch long, including their wings. Their bodies are often a dark brown or reddish-brown color. They possess four wings of equal size that may appear transparent or smoky, featuring heavy venation with three or more thick, pigmented veins running along the leading edge of the forewing.
The soldier caste is responsible for defending the colony. Soldiers are recognizable by their large, heavily armored heads, which can be blocky or rectangular in shape. Their powerful, tooth-like mandibles protrude forward, making them incapable of feeding themselves, so they rely on other colony members for sustenance.
The third group consists of nymphs, also sometimes referred to as false workers, who perform the labor within the colony. These nymphs are soft-bodied, wingless, and creamy white or pale in color. They are found exclusively within the wood galleries, where they excavate tunnels, feed the soldiers, and tend to the young.
Key Differences from Subterranean Termites
Identifying drywood termites often involves distinguishing them from the more common subterranean species, which have very different habitat requirements. Subterranean termites require consistent contact with soil or a source of high moisture to survive, which is why they construct distinctive mud tubes to travel above ground. Drywood termites, conversely, live in relatively dry wood and extract the moisture they need from the cellulose they consume, meaning they never build mud tubes.
Visual differences are also apparent when comparing the winged reproductives of both species. Drywood alates typically have three or four thickened, pigmented veins along the front edge of their wings, while subterranean alates usually have only two. Drywood swarmers often have an orange-brown head and pronotum, and their wings may appear smoky. Subterranean swarmers, in contrast, are often uniformly dark brown or black with lighter-colored wings.
The soldier castes also present structural differences that aid in identification. Drywood termite soldiers are characterized by their large, robust heads that are often blocky or rectangular. Their pronotum (the shield-like segment behind the head) is typically as wide as or wider than their head. Subterranean termite soldiers tend to have narrower, more elongated heads, and their pronotum is narrower than their head.
Recognizing the Signs of Infestation
Since drywood termites rarely venture outside the wood, homeowners must look for the physical evidence of their activity rather than the insects themselves. The most important indicator is the presence of fecal pellets, known as frass, which the termites expel from their tunnels. Drywood termite frass is expelled through small openings called kick-out holes, which the termites often seal up after disposal.
The pellets are hard, dry, and uniform in size, generally measuring about 1 millimeter in length. They are characterized by a unique hexagonal or six-sided shape, often with concave sides. The color of the frass varies depending on the specific wood the colony is consuming, and it is usually found accumulated in small piles directly beneath the infested wood.
Another sign of an active or recent infestation is the presence of discarded wings. After a reproductive swarm, alates shed their wings when they settle to establish a new colony. These detached, equal-sized wings may be found in small piles on windowsills or near light sources. Inside the wood itself, drywood termites excavate smooth, clean galleries that run with or against the wood grain. Unlike the damage caused by subterranean termites, these tunnels contain no mud or soil.