Washington produces a specific set of pest problems, and most of them are downstream of the same two facts: it rains for eight months west of the Cascades, and the housing stock was built with vented crawlspaces under it.
That combination gives you moisture ants, carpenter ants, dampwood termites, wood-rotting fungus, Oriental cockroaches, and rodents with a warm dry void to move into every October. It is a different pest calendar from the one national pest control content describes, and buying against the wrong calendar is how people end up paying for the wrong treatment.
Bed bugs are the specialism — the hardest job on this list to buy well, and the one where a bad purchase costs the most. But the exterminators we work with across Washington handle the full range. If you have rodents in the attic and a wasp nest under the eave, that is one visit, not two.
The Washington pest calendar
Almost every pest on this page has a season, and knowing which one you are in tells you whether what you are seeing is normal or a warning.
The two halves of the state run the same shape on slightly different dates. Eastern Washington is colder and drier, which pushes rodents indoors earlier and takes most of the moisture-dependent species off the board entirely.
| When | What moves | Why |
|---|---|---|
| February to April | Carpenter ant swarmers, subterranean termite swarmers | Winged reproductives leave established colonies on the first warm damp days. Indoors, a swarm means the colony is already in the structure. |
| April to June | Odorous house ants, pavement ants, wasp queens founding nests | Foraging begins in earnest as ground temperatures rise. A nest removed in May is the size of a golf ball; the same nest in August is the size of a football. |
| July to September | Yellowjackets at peak, fleas at peak, dampwood termite flights | Colonies reach maximum size and switch to sugar-seeking. Warm humid indoor conditions run the flea life cycle at its fastest. |
| Late August to October | House spiders wandering, cross orbweavers at full size | Mature males leave their webs to find females. The spiders were always there; this is the fortnight they cross the living-room floor. |
| October to December | Rats and mice, cluster flies, overwintering beetles | The first sustained cold and rain. Callouts spike within a fortnight of the weather turning, every year, in both halves of the state. |
| All year | Bed bugs, German cockroaches, Oriental cockroaches | Indoor species living in heated buildings. Nothing outside affects them, which is why they arrive at times of year that make no seasonal sense. |
The last row is the one worth pausing on. Bed bugs and German cockroaches track human movement rather than weather — turnover, travel, second-hand furniture, shared laundry — which is why a January infestation is exactly as likely as a July one.
If you are dealing with either in a multi-unit building, the apartments and multi-family page covers why treating one unit in a connected structure reliably fails.
The eight services, and what changes in each
Each of these has its own page with Washington-specific detail, cost ranges, and the mistakes worth avoiding. The short version is below.
Rat and mouse control
The biggest callout category in Washington and the one most tied to the calendar. Roof rats travel utility lines and overhanging branches into attics across the Puget Sound corridor; deer mice arrive in rural and eastern Washington properties and bring a health question with them. Trapping clears the animals already inside. Sealing every gap wider than a pencil is what stops the next ones, and a quote with no exclusion component is a subscription rather than a fix.
Ant control
Odorous house ants are the everyday indoor ant west of the Cascades — crush one and it smells faintly of rotten coconut, which is the fastest field identification available. Pavement ants take the drier eastern half and the seams of driveways and slabs everywhere. Neither damages a building. Both are baited rather than sprayed, because spraying a trail kills the foragers and leaves the queen producing replacements.
Moisture and carpenter ant control
The genuine western Washington structural problem, and the one worth understanding before anyone quotes. Carpenter ants excavate galleries in wood that damp has already softened. Moisture ants go further — they colonise wood that is actively rotting, so finding them is usually finding a leak. Neither species eats wood. Both are telling you something about the building that a spray does not address.
Spider control
Almost entirely a nuisance and anxiety problem rather than a medical one, and the honest version of this page says so. Giant house spiders and cross orbweavers dominate the autumn wandering season from late August. The hobo spider spent two decades wrongly blamed for necrotic bites and current research does not support it. Black widows are genuinely present in the dry eastern half of the state and genuinely absent from most of the west.
Wasp and hornet nest removal
Yellowjacket colonies peak in August and September, which is exactly when they switch to seeking sugar and start turning up at every outdoor table in the state. Ground nests and wall-void nests are the two that need a professional. The one thing never to do with a wall-void nest is plug the entrance — a colony denied its exit chews inward, into the room.
Cockroach control
German cockroaches in multi-unit housing behave almost exactly like bed bugs: they travel between units, a single treated apartment gets reinfested from next door, and the fix is a building programme rather than a unit callout. Oriental cockroaches are the damp-basement and crawlspace species that Washington housing stock produces reliably. Foggers make both worse.
Flea treatment
Essentially one species statewide — the cat flea, on cats and dogs alike. The adults on the animal are a small fraction of the population; the rest are eggs, larvae and pupae in carpet, bedding and floor cracks. Pupae survive treatment by design, which is why a house appears to reinfest a fortnight later. Treating the animal and the building on the same day is the only version that works.
Termite inspection and treatment
Washington has Pacific dampwood termites and western subterranean termites, not the drywood and Formosan species every national template describes. A complete wood-destroying organism inspection here is a regulated product with its own licence requirement and a control number on the report, and it covers rot fungus and carpenter ants alongside termites — which in this state is usually what it actually finds.
When a pest problem is really a building problem
This is the section that separates a useful pest control company from a spray-and-invoice operation, and it is worth knowing before you take the first quote.
Four of the pests on this page do not cause the condition that brought them. Moisture ants colonise wood that is already rotting. Dampwood termites need wood at high moisture content and cannot establish in dry timber. Wood-rotting fungus is the actual destructive agent in most Washington structural damage findings. Oriental cockroaches need standing damp and will not persist in a dry crawlspace.
Treat any of the four without addressing the water and the population returns, because the habitat is still there.
The usual sources in Washington housing are unglamorous and repetitive: a failed roof or gutter line dumping water at the foundation, siding or trim in ground contact, a crawlspace vapour barrier that was never fully laid, a plumbing leak under a bath, and decking or planters fixed directly to a wall.
A competent inspector will tell you which one they found. Ask what they saw, not only what they intend to spray.
What pest control costs in Washington
Pest control is priced on the job rather than from a rate card, so these are 2026 ranges with the reason each one is wide. Anyone quoting a firm number before seeing the property is quoting the visit, not the work.
| Job | Typical range | What moves it |
|---|---|---|
| One-off callout, defined problem | $150 – $350 | Whether a follow-up visit is included, and travel distance from the operator’s base. |
| Quarterly recurring plan | $100 – $175 per visit | Property size, whether the exterior perimeter is included, and how many structures sit on the lot. |
| Rodent trapping programme | $250 – $600 | Number of visits needed to clear and confirm. Attic and crawlspace access difficulty. |
| Rodent exclusion (sealing) | $300 – $3,000+ | This is carpentry, not pest control. A few gaps and a vent screen sits at the bottom; a full crawlspace re-screen with subfloor repair sits well above it. |
| Wasp or hornet nest removal | $150 – $400 | Accessible aerial nest at the low end. Ground nests, wall voids and anything above single-storey ladder height at the high end. |
| Carpenter or moisture ant treatment | $250 – $600 | Whether the nest is located or only the trail. Satellite nests inside a structure need repeat visits. |
| German cockroach programme | $200 – $400 per unit | Three to four visits is standard. Per-unit cost drops sharply on a building-wide programme. |
| Flea treatment | $150 – $400 per visit | Almost always two visits, timed for the pupal window. Square footage of soft flooring drives the rest. |
| Complete WDO inspection | $150 – $400 | Crawlspace and attic access. Required for most property transfers and refinances. |
| Subterranean termite treatment | $1,200 – $3,500 | Linear feet of foundation, whether trenching or slab drilling is needed, and warranty length. |
Bed bug treatment sits apart from all of these because it is priced per room and has to reach every life stage including eggs. Chemical treatment runs $270 to $775 per room across two or three visits; heat runs $400 to $900 per room in one.
The bed bug cost page carries the full table and explains why two quotes on the same property can differ by thousands of dollars without either of them being dishonest.
What a licensed Washington operator should do
Applying pesticides for hire in Washington requires a current WSDA applicator licence. Complete wood-destroying organism inspections require a separate structural pest inspector licence, and the resulting report carries an inspection control number and follows a form prescribed in WAC 16-228-2005 onward.
Both licences are public. Ask for the number before work starts; a legitimate operator supplies it without being pressed.
Beyond the paperwork, the things worth insisting on are the same across every pest on this page. A written finding that names the species and where it was found, rather than “ants”. A treatment plan that says what is being applied and where. An explicit note of what conducive conditions were observed — the moisture, the gap, the harbourage — because that is the part you have to fix and they cannot. And a follow-up visit built into the price rather than sold to you afterwards.
Here is how we work, plainly. We are not the exterminator — we take the call, find the company that covers your ZIP code, and put you straight through to them at no cost to you. They quote you and they do the work. If nobody covers your ZIP, we say so on the call rather than taking your details anyway.
Where this covers
Coverage is set by ZIP code, not by city name, and in Washington that distinction matters more than it sounds. USPS preferred city names do not follow municipal boundaries: Shoreline, Burien, SeaTac, Tukwila and Des Moines addresses all carry a Seattle USPS name, and most of Spokane Valley carries Spokane. All of them are covered.
The service areas directory lists all 25 county areas and every covered city with its ZIP count.