Pest control in Washington follows wet wood on the west side and warm shelter on the east side. Carpenter ants move into lumber that a leak has already softened, which is common where the damp season lasts for months. Roof rats and house mice use ivy, woodpiles, and gaps at the eaves to reach an attic. East of the Cascades, mice head for wall voids when the nights freeze, and wasps build under eaves in the dry months. The insect you saw and the moisture you ignored are often the same visit.
Tell the truth about the evidence. Wings on a sill, fine frass under a sill plate, scratching in the ceiling after dark, a nest under a deck, or droppings in the pantry are different jobs. Say whether pets or children live in the house, and whether the kitchen is the problem or the perimeter is. A treatment that skips the wet wood feeding carpenter ants will not end the colony. If you are not sure of the species, describe the insect and where you found it instead of guessing a name.
Walk the outside before you call. Note gaps at the garage door, limbs on the roof, firewood against the siding, and pots or drains that hold water. On the wet side a rotten corner board is an invitation. On the dry side a gap at the foundation is a winter door. Yellowjackets in a wall void are a different urgency from ants in a bath. Say which one is active this week, and how long you have noticed it.
If a wall is about to be opened for a repair, say so, because the nest and the leak should be understood before the cavity is closed again. Mention the town. A photo of the insect or the damaged wood helps, but the first job is a clear sentence. Do not wait for a second season of wings to be sure you have a problem.
Wet wood and a cold night will keep offering shelter. Call with the town, what you saw, and whether a leak is part of the same house. Call the number on this page.