Ants are beneficial to the environment until they get in your home or buildings then they become  pests .Most of the ant damage and nuisance compliant calls are in city of bellevue, kirkland,Redmond,Mercer island,Sammamish,Issaquah,Medina,Yarrow point in washington  may be nesting outdoors and invading the house to find food.
It is not uncommon for colonies to establish satellite colonies indoors, while the main or parent colony remains outdoors.
Ant reproductive swarms from outdoor colonies may establish themselves in houses too.
It is important to locate the access points into the house and seal them. Ants often enter the house through door and window trim, holes around plumbing and wiring, etc.

Making it difficult to reach their food source will encourage the pests to look elsewhere for food.Seeing large numbers of winged ants in your house is often a clue that the nest is indoors.However, finding the nest can be quite difficult.Nests are commonly found in the following locations.
soil around or under the house, beneath sidewalks and driveways, along steps and foundations,under debris and rocks, in stumps or other damp, decayed wood, in trees, and in lawns.Some common nest locations include decaying structural timbers, attics, wall and floor voids,under sinks, behind cabinets, and many similar hard-to-reach places.

Ants require moisture to survive, so remove any decay in building.

— Home infestations are often traced to the lawn, so treating the lawn often solves the problem. A chemical barrier is a temporary but effective treatment if applied around the outside of the house.

— Foraging worker ants are quick to find crumbs, grease, food scraps and food in open or partly open containers. Keep the kitchen clean.

— Insecticides can get rid of ants indoors, but they don’t eliminate the root of the problem — the colony. If you use an insecticide indoors, buy one made for indoor use.

— Treating the trails that ants follow inside from their outdoor nest will often discourage them from coming in again. If you can find the trail, follow it to the nest and treat it with a labeled insecticide. Always read labels before using one of these products.