Signs of Termite Activity in Seattle This Spring
As temperatures rise and Seattle moves out of its wet, slow winter into a season of warming days and lingering ground moisture, many homeowners don’t think about pests beyond the usual spring pests—but termites are a major exception. The Pacific Northwest’s mild, damp climate creates ideal conditions for several types of termites that can infest homes and structures. Spring is often when termite activity becomes more noticeable: colonies become more active after winter, moisture from heavy rains and melting snow softens wood, and winged reproductives (swarmers) may emerge to start new colonies. Because termite damage is usually hidden and accumulates quietly, early recognition of warning signs is essential to limit costly repairs.
There are several common indicators of termite presence that Seattle residents should watch for this spring. Mud tubes or tunnels running along foundations or across crawlspaces are a telltale sign of subterranean termites moving between soil and wood. Discarded translucent wings on windowsills, porches, or near light sources often point to recent swarming. Wood that sounds hollow when tapped, buckling floors, blistered or peeling paint, and unexplained sagging in ceilings or walls can all signal internal feeding. In some species common to the region—especially those that prefer damp or decaying wood—you may also find tiny pellet-like droppings (frass) or visible damage in moist wood around leaky plumbing, rooflines, decks, stumps, or fallen trees.
Prompt action matters. If you spot any of these signs, a timely inspection by a qualified pest professional can determine the species, extent of infestation, and best treatment or prevention plan. Simple changes around the property—reducing wood-to-soil contact, improving drainage and ventilation, repairing leaks, and keeping mulch away from foundations—can reduce risk, but established colonies often require professional intervention. This article will walk Seattle homeowners through the specific signs to look for this spring, how to differentiate types of termite activity, and practical next steps to protect your home.
Winged swarmers and piles of discarded wings
Winged swarmers (alates) and their discarded wings are among the most obvious early signs of termite activity. The alates are reproductive termites that fly out to start new colonies; after landing and pairing off, they shed their wings, leaving behind small translucent wing fragments. In a home this can show up as tiny piles of glossy, symmetrical wings on windowsills, near exterior doors, light fixtures, or baseboards. Because termite wings are generally longer and more uniform than ant wings, and because termite wings break off cleanly at the base, finding many matching wing pairs is a strong indicator that termites—not flying ants—have been present.
In Seattle, springtime weather creates the conditions that trigger swarming, so homeowners should be especially vigilant now. Warmer, calm days after rain are common in the Pacific Northwest during spring, and those conditions prompt both subterranean and dampwood termites to send out winged reproductives. Seattle’s older housing stock, frequent wood in construction and landscaping, and generally moist environment can all increase the chance that swarmers will be produced close to or inside buildings. If you notice swarmers or discarded wings inside, or an accumulation outdoors near light sources and eaves, treat that as potentially active termite activity that warrants further inspection.
If you find swarmers or wing piles in or around your Seattle home this spring, take photos and collect a few wings in a sealed container for identification, but avoid crushing or disturbing dense infestations. Check nearby entry points—window frames, door thresholds, attic vents, and crawlspaces—and look for corroborating signs such as mud tubes, frass, or soft/crumbly wood. Reduce conducive conditions by eliminating wood-to-soil contact, fixing leaks and drainage problems, and removing stacked firewood or mulch close to the foundation. Because swarms indicate reproductive activity and potential colony establishment, schedule a professional inspection promptly if you suspect termites; a licensed technician can confirm the species, assess the extent of infestation, and recommend appropriate monitoring or treatment options for the local Seattle environment.
Mud tubes and soil tunnels on foundations and exterior walls
Mud tubes are pencil- to thumb-sized, hardened soil tunnels that subterranean termites build to travel between their underground nests and exposed wood without drying out or being exposed to predators. They are constructed from soil, chewed wood, saliva and feces, and typically hug foundations, run up exterior walls, or cross cracks and gaps where the soil meets the structure. Fresh tubes often look moist and intact and will crumble if scraped; older, inactive tubes look dry, pale and crumbly. Because they follow a continuous path from soil to wood, finding a mud tube on your foundation is a strong indicator that termites are actively foraging on or inside structural wood nearby.
In Seattle this spring, conditions often favor termite activity: warming temperatures and lingering moisture after winter rains make subterranean termites more likely to forage and repair damaged tubes. Look for newly repaired or damp-looking tubes after dry periods—if a tube you disturb is rebuilt within a day or two, that indicates an active colony. Inspect around foundations, where downspouts discharge, along retaining walls, under eaves, and in crawlspaces and basements; interior signs often follow exterior tubes, so check baseboards and sill plates where tubes meet the structure. Keep in mind mud tubes differ from root growth or erosion channels by their uniform, packed soil texture and by their deliberate route to wood.
If you find mud tubes, reduce the factors that encourage termite access and call a licensed pest-control professional for a thorough inspection and treatment plan. Immediate homeowner steps include removing wood-to-soil contact (firewood, mulch, planter boxes), fixing grading and drainage so soil slopes away from foundations, repairing leaky gutters and pipes, and ensuring crawlspaces are ventilated and dry. Photograph or document any tubes you find and monitor whether disturbed tubes are rebuilt; persistent or extensive tubing generally requires professional assessment and treatment options such as targeted baits or barriers to protect the structure.
Termite droppings (frass) or pellet-like debris near wood
Termite droppings, commonly called frass, are small, pellet-shaped deposits pushed out of galleries by certain kinds of termites (most notably drywood species). They often look like coarse sawdust or tiny grains of coffee grounds, but the pellets are fairly uniform in size and shape — usually hexagonal or rounded at the ends — and tend to accumulate in small piles beneath kick-out holes, along baseboards, inside window sills, behind trim, or under infested furniture. Because frass is ejected from living galleries, finding fresh, slightly glossy or moist pellets is a strong indicator of an active colony; older pellets dry to a dull, powdery appearance. Carpenter ant debris can look like sawdust too, but it usually contains wood fibers and insect parts and is less uniform than true termite pellets.
In Seattle this spring, signs of termite activity often come together: warmer, wetter conditions encourage subterranean termites to be more active, and spring swarm flights can bring winged reproductives out of nests looking for new sites. In the Pacific Northwest, subterranean species are more common and typically leave mud tubes and soil-packed tunnels rather than frass, whereas drywood or dampwood infestations — which produce the recognizable pellets — are more likely to be associated with isolated piles of frass in attics, furniture, or dry structural timbers. After periods of rain followed by warm days, check common frass locations (eaves, attics, window framing, deck joists and below siding) as well as areas where wood contacts soil or where moisture has softened wood; spotting fresh pellets during spring is a useful early warning that an inspection is needed.
If you find pellet-like debris, document it (photos from several angles), note where the material accumulates, and inspect adjacent wood for softening, small exit holes, or hollow sounds when tapped. While a homeowner can clear small piles to see if more appear, do not assume sporadic debris is harmless — fresh frass usually signals an active colony and potential ongoing damage. Immediate steps you can take include reducing moisture sources (fix leaks, improve ventilation, remove wood-to-soil contact, limit mulch against foundations) and isolating or removing obviously infested furniture. For confirmation and treatment options — which vary by termite type (localized removal or spot treatments for limited drywood infestations, fumigation for heavy drywood infestations, or baiting/liquid barriers for subterranean species) — contact a licensed pest professional familiar with Seattle conditions to assess the scope and recommend a safe, effective plan.
Hollow, softened, or crumbling wood and blistered paint
Hollow, softened, or crumbling wood and blistered or bubbling paint are classic signs that wood has been eaten from the inside. Termites consume the cellulose in wood, often leaving a thin veneer of surface wood or paint while tunneling through the interior, so a quick tap or probe with a screwdriver will reveal a hollow sound, soft give, or collapse. Blistered paint can occur when termites create galleries directly under the finish or when their activity increases local moisture; because the surface can still look intact, probing and checking the underside of sills, joists or trim is important to confirm whether the problem is decay, rot, or active termite damage.
In Seattle this spring, these symptoms deserve extra attention because the region’s cool, wet climate and seasonal warming can increase termite activity and wood moisture levels. Local termite species that favor damp or soil-contact wood are more likely to exploit wet framing, decks, siding, and stored lumber, and spring swarming or increased foraging after rainy spells makes interior and exterior inspections more urgent. Check common trouble spots — crawlspaces, basements, window sills, door frames, eaves, porch beams and areas where wood contacts soil or is shaded and damp — and look for hollow-sounding boards, crumbling edges, blistered paint, and any accompanying signs like discarded wings, mud tubes, or frass.
If you find softened or hollow wood or blistered paint, take photos and mark the area, then reduce conditions that attract termites: fix leaks, improve ventilation in crawlspaces, clear vegetation and wood debris away from foundations, keep firewood off the ground and away from the house, and ensure gutters and grading keep water away from the structure. Because hollow or crumbling wood can indicate an active infestation or longstanding structural damage, arrange a thorough inspection by a licensed pest control professional who can confirm whether termites or fungal rot are the cause and recommend appropriate treatments (localized repairs, moisture remediation, baiting or termiticide options) and a monitoring plan to protect the home going forward.
Sticking or sagging doors, warped floors, and other structural symptoms
Sticking doors, sagging floors and warped surfaces are common early indicators that wood in the structure has lost strength or dimensional stability. Termites consume the cellulose inside wood, often leaving a thin veneer or paint surface intact while hollowing the interior. That internal damage can allow doors to bind in their frames, floors to feel springy or uneven, and trim or baseboards to pull away as structural members shift. Because these symptoms are mechanical rather than visual, homeowners may notice functional changes first—doors that suddenly stick after a dry spell or floors that creak in a new area—so physical changes in how the house operates are an important red flag.
In Seattle this spring, a few seasonal and regional factors make those structural symptoms particularly meaningful. The region’s cool, wet climate favors dampwood termites, which infest moist or decaying wood such as foundation timbers, decks, and siding, and subterranean species that exploit high-humidity crawlspaces and soil-contact framing. Spring is also peak swarming time for many local termite species; finding discarded wings, seeing swarmers, or noticing mud tubes along foundations at the same time you experience sticking doors or warped floors strongly increases the likelihood that termites are responsible rather than simple moisture-driven swelling. Check areas that retain moisture—bathroom subfloors, crawlspaces, window sills, and around roof leaks—because termite damage in Seattle often co-occurs with chronic damp conditions.
When you notice these structural symptoms, act promptly to limit further damage. Start with a careful visual and tactile inspection: press or tap suspicious wood to detect soft, hollow sounds; look inside closets, basements and crawlspaces for mud tubes, frass, or expelled wings; and note any new moisture sources such as leaks or poor drainage that should be corrected. Because identifying species and the extent of infestation affects treatment choices, contact a licensed pest professional for a thorough inspection and written plan if termite activity is suspected. In the meantime, reduce wood-soil contact, fix leaks, improve drainage and ventilation, and remove stacked firewood or debris near the house to lower the favorable conditions that allowed the infestation to develop.
