Wasp work in Washington is almost entirely a late-summer problem, and the reason is arithmetic rather than temperament.
Every colony in the state started in spring as a single overwintered queen. By mid-August it has been building for four months and is at maximum size. At the same time the brood-rearing phase finishes, so workers stop hunting protein for larvae and start seeking sugar — which is exactly when they begin arriving at bins, fallen fruit and outdoor tables in numbers.
What you are looking at
| Type | Nest | Behaviour |
|---|---|---|
| Paper wasps | Small open comb with visible cells, hanging from a short stalk. Under eaves, in gutters, inside pipe ends and BBQ covers. | Comparatively unaggressive and will usually tolerate people passing. The European paper wasp is now widespread across the state and is the one most often found in odd cavities. |
| Yellowjackets, ground-nesting | Enclosed paper nest inside an old rodent burrow or void in the ground. Entrance is a single hole with steady traffic. | Highly defensive. Most stings in Washington come from someone running a mower or strimmer over an entrance they never saw. |
| Yellowjackets, cavity-nesting | Inside wall voids, attics, soffits and floor cavities, entering through a gap in siding, a vent or a utility penetration. | The job that most needs a professional, and the one where the common DIY response causes the most damage. See the warning below. |
| Bald-faced hornet | The large grey football-shaped aerial nest in a tree, shrub or under an eave. Can reach the size of a basketball. | Despite the name it is a yellowjacket, not a true hornet. Very defensive of the nest and quick to respond in numbers. |
The northern giant hornet question
Washington spent five years as the only US state with a confirmed northern giant hornet population, after the first detection in Whatcom County in 2019. That is over.
On 18 December 2024, WSDA and USDA announced that the species had been eradicated from Washington and from the United States, following three consecutive survey years with no detections — the standard threshold for declaring an eradication successful.
Reporting a suspected sighting is still worthwhile, because public reporting is how a reintroduction would be caught early, and WSDA maintains a reporting route for exactly that. But if you are looking at a very large wasp in Washington in 2026, the realistic candidates are a bald-faced hornet, a European hornet, a western cicada killer, or one of several large native look-alikes. WSDA publishes a side-by-side identification guide.
When it is a homeowner job and when it is not
A small, fully visible paper wasp nest, early in the season, on a wall you can reach standing on the ground, treated at dusk when the colony is in and inactive, is a reasonable DIY job.
Three situations are not, and it is worth being blunt about why.
Any nest in a wall void or attic. You cannot see the size of it, you cannot reach it directly, and the failure mode is the one described above.
Any ground nest. The colony is larger than the entrance suggests, the response to disturbance is immediate and collective, and you have nowhere to retreat to that they cannot follow.
Anything needing a ladder. Most serious wasp injuries in Washington are fall injuries rather than sting injuries. Being stung on a ladder is how people come off ladders.
Add to that anyone in the household with a known sting allergy, in which case none of this is a DIY question at all.
What reduces the problem next year
Queens found new nests in spring, so the useful work is done in April and May rather than August. Check eaves, soffits, gutter runs, sheds, open pipe ends, unused BBQs and roof voids for early nests the size of a golf ball, when a single queen is present and removal is trivial.
Then close the cavities. Screen or seal the gaps in siding, vents and utility penetrations that gave last year’s colony access, once you are certain it is inactive. Keep bins lidded and rinse recycling from July, because sugar residue at the kerb is what concentrates foraging workers around a doorway in August.
What nest removal costs in Washington
An accessible aerial nest runs $150 to $400 in 2026. Ground nests, wall voids and high or awkward access sit at the top of that range or above it, because the work takes longer and needs more equipment.
Ask whether a return visit is included where a cavity nest needs confirming clear, since that is the one most likely to need a second look. Removing an old nest after the season is cosmetic — in this climate nests are not reused. The statewide pest control page carries the full cost table across all eight services.