Carpenter ants: The Silent Destroyers
Carpenter ants (Camponotus spp.) are the most damaging ant species in Washington. They don't eat wood; they excavate it to create smooth tunnels for nesting. A mature colony can have up to 50,000 workers and multiple satellite nests. The main nest is usually outside in a tree stump, dead log, or wood pile, while satellite nests are inside wall voids, attics, or under insulation. Signs of carpenter ants include sawdust piles (frass) that contain wood shavings, ant parts, and insect exoskeletons. You may also hear a rustling sound in walls, especially at night. Winged swarmers appear in spring (March–May) and are often mistaken for termites. Carpenter ants have a narrow waist, bent antennae, and front wings longer than back wings—termites have a broad waist, straight antennae, and equal-length wings. Treatment requires locating all nests, which often involves a thorough inspection with moisture meters and borescopes. We drill small holes into suspected areas and inject insecticidal dust. Removing moisture sources and repairing rotten wood is crucial to prevent reinfestation. The cost for carpenter ant control typically ranges from $300 to $600, plus any structural repairs.
Why ants Invade Your Home in Spring and After Rain
In Washington, ant activity peaks in spring (March–May) when temperatures rise and colonies produce swarmers. After a heavy rain, ants often invade homes because their outdoor nests flood. They seek dry shelter and food. This is especially common in Western Washington, where rainfall averages 37 inches annually. Odorous house ants are notorious for marching indoors after rain. They emit a rotten coconut smell when crushed and are attracted to sweets. Pavement ants nest under sidewalks and driveways; when it rains, they move into nearby buildings. To prevent rain-related invasions, ensure your yard has proper drainage, gutters are clean, and the foundation is sealed. Treated with a barrier spray before the rainy season can stop them before they enter.
Choosing the Right Ant Bait for Your Species
Ant baits work because ants feed on them and share the poison with the colony. But different ants prefer different foods. Odorous house ants love sweets, so a sugar-based gel bait works well. Pavement ants prefer greasy foods, so a protein-based bait is better. Carpenter ants are omnivorous but often prefer sweets; they also need large amounts of bait to affect the colony. Using the wrong bait can make the problem worse. If you use a bait that ants don't find attractive, they'll ignore it. Also, don't spray repellent insecticides near baits—ants will avoid both. Professional exterminators carry a variety of baits and know which one to use based on an on-site identification. They also know how to place baits in high-traffic areas without contaminating food preparation surfaces.
The Role of Moisture in Ant Infestations
Moisture is the number one attractant for ants in Washington. Leaky pipes, damp crawlspaces, wet wood, and condensation attract carpenter ants, odorous house ants, and many others. Carpenter ants specifically require moist wood to nest; they cannot excavate dry, sound wood. Therefore, any water damage in your home increases the risk. To reduce moisture, fix plumbing leaks immediately, ensure bathroom fans vent outside, use a dehumidifier in basements, and slope the ground away from your foundation. Replace any water-damaged wood. Regular inspections by a professional can catch moisture issues before they lead to an ant infestation. We include a moisture assessment in our inspection terms that vary by provider.
Major-City Ant Guides in Washington
Property conditions vary across Washington, so the state overview should lead readers to city guidance without treating a city name as a diagnosis. The linked guides cover major local building, moisture, landscape, and access considerations while keeping species identification and provider terms property-specific.
What surveys and cost guides say about ant problems
Homeowners often ask whether an ant problem is unusual and whether a quoted price is normal. Public research cannot answer either question for one house, but it does set expectations. Here is what the sources report. Fifty-four percent of ant-control professionals surveyed by the National Pest Management Association (NPMA) in late 2011 and early 2012 said ant infestations were increasing, a view of surveyed pros at the time rather than a measured change in infested homes. Summer was the most-cited peak season in the National Pest Management Association (NPMA) survey of professionals in 37 states in 2011–12, chosen by 67%; respondents could select several seasons, and this is historical pro experience rather than a household infestation rate. The National Pest Management Association (NPMA) survey of professionals in 37 states in 2011–12 found that one in five, 20%, reported ant jobs usually requiring three treatments; the number describes responding pros, not households, and is historical. Eighty-eight percent of the ant-control professionals surveyed by the National Pest Management Association (NPMA) in late 2011 and early 2012 said they had treated ant infestations in offices, a historical figure about where pros worked, not a share of offices infested. If you have been ignoring scratching in the walls, you are not alone: 17% of the 2,000 U.S. respondents in ConsumerAffairs' February 2024 survey of 2,000 U.S. respondents reported taking no action against pests, though the self-reported, pest-and-mold survey offers context, not an infestation rate. If one number should shape your next step, it is how often do-it-yourself attempts fall short. That is not an argument against trying, but it is a reason to set a deadline and call a professional if the problem persists past it.