Just like flies, gnats and beetles, ants are a household nuisance. Some, such as carpenter ants, can damage your home. Ants are constantly on the lookout for food, water, and safe places to build nests. Since they're very small, ants can enter into your home by finding the tiniest crack or crevice. Their smallness also makes them hard to detect, unless you see several of them at once. To find ants that are invading your house, you have to know where to look.
Inspect the outside of your house to find where ants are getting in. Search for ant nests in the soil, as well as ants around the foundation of your house. Check around sidewalks. The ants can leave their nests and enter your home looking for food, water, or shelter. Ants can search as far as 100 feet from their nest, according to Cecalaveras.ucdavis.edu. So, expand your search that far all the way around your house. Once you find a nest, look for lines of ants or activity that leads to your house.
Inspect the basement or the crawl space, using a flashlight. Look particularly around leaky pipes, dripping hot water heaters, your washing machine, and other damp or wet areas. Ants are attracted to warm, damp places. You may find them in rotted wood and timbers. If you find ants, watch to see if they exit the basement or crawl space. Then you'll know where they're coming in.
Inspect the main floors of your home. The rooms they'll most likely be in will have food and water sources. Look especially in your kitchen, dining room, and around bathtubs, toilets, and pipes. Check around leaky window sills, baseboards, and around countertops where food and crumbs may be present. Once you find the ants, track them to find out how they're getting in.