Termites are present in Washington State and represent a significant risk to property owners. The state’s mix of older homes and a generally damp climate, particularly west of the Cascade Mountains, creates an environment where wood-destroying insects thrive. Understanding the local risk is important because these pests can cause substantial structural damage before any visible signs appear. Homeowners need vigilance and knowledge of the types of termites that inhabit the Pacific Northwest. Termite activity is a year-round concern, with various species adapting to the moisture and temperature conditions found throughout Washington State.
Termite Species Common in Washington State
The primary termite threats in Washington State belong to two main groups: the Pacific Dampwood termite and the Western Subterranean termite. Each species has distinct habitat and moisture requirements that determine where they are most likely to infest a structure. The Pacific Dampwood termite (Zootermopsis angusticollis) is the largest species in the region, with winged forms sometimes exceeding one inch in length. They live and feed within wood that has a high moisture content, often due to leaks, poor ventilation, or direct wood-to-soil contact.
Dampwood termites do not require contact with the soil to establish a colony, instead relying on the water-saturated wood itself for sustenance. Conversely, the Western Subterranean termite (Reticulitermes hesperus) maintains its primary colony in the soil, which serves as its essential source of moisture. Subterranean termites construct mud tubes to travel between their underground nest and the wood structure they are attacking, thus avoiding open air.
Subterranean termites are considered the most destructive, as they can infest any wooden structure, even those that are relatively dry, provided they can maintain a connection to the soil. Dampwood termites often indicate a pre-existing moisture problem, and eliminating the water source is the primary step in control. A third type, the Drywood termite (Incisitermes minor), is rarely established in Washington State, usually only appearing in imported furniture or lumber from southern regions.
Visual Evidence of Infestation
Homeowners should look for specific physical evidence to confirm a termite infestation, as the signs differ depending on the species involved. One of the clearest indicators of an active colony is the appearance of discarded wings, often found on window sills, near light sources, or in spiderwebs. These wings are shed by “swarmers,” or winged reproductives, that emerge from a mature colony to establish a new one, typically during warm, humid weather.
For Western Subterranean termites, the most diagnostic sign is the presence of shelter tubes, which are pencil-sized tunnels made of soil and wood particles. These mud tubes run along foundation walls, support beams, or crawl space floors, offering the termites protection and a pathway between the soil and the wood they consume. Subterranean termite damage leaves wood with a layered, honeycombed appearance, often packed with moist soil and fecal material.
Pacific Dampwood termites do not create mud tubes and instead pack their galleries with loose, dark fecal pellets. Drywood termites, which are rare, produce distinctive, hard, six-sided fecal pellets, known as frass, which they push out of “kick-out” holes in the infested wood, often forming small piles. Tapping on suspected wood and hearing a hollow sound can also indicate internal tunneling by any species, as termites consume the interior, leaving only a thin outer shell.
Mitigation and Prevention Strategies
Preventing a termite infestation in Washington State focuses heavily on controlling the moisture that is attractive to both dampwood and subterranean species. Homeowners should ensure that all plumbing is leak-free and that gutters and downspouts effectively direct water away from the foundation. Poor ventilation in crawl spaces can lead to high humidity, which fosters the wood-decaying conditions favored by Pacific Dampwood termites.
Structural Modifications
Structural modifications are important, particularly eliminating any wood-to-soil contact around the home’s perimeter. This includes removing wood debris, storing firewood away from the structure, and ensuring that siding or skirting is not touching the ground.
Wood that is already damaged by moisture or decay should be removed and replaced, as this material is a prime target for dampwood termites. For Western Subterranean termites, creating a chemical barrier in the soil adjacent to the foundation is an effective remedial control measure. Regular professional inspections of the foundation and crawl space can help detect the subtle signs of activity, such as early mud tube formation, before extensive damage occurs.