Seattle Centipede & Millipede Infestation — Reading the Underlying Cause
Centipedes and millipedes require specific conditions to establish in significant numbers — and those conditions are almost always correctable. In Seattle properties, consistent centipede or millipede activity points to excess moisture in the basement or crawlspace, organic debris accumulation around the foundation, or an underlying insect population that centipedes are following as a food source.
Millipedes, which feed on decaying organic matter, often invade in large numbers after heavy rainfall — migrating from outdoor mulch and leaf litter into foundations and through gaps in the building envelope. Centipedes follow the insects they feed on.
Identifying Which Species You Have in Seattle
Centipedes are fast-moving predators with one pair of legs per body segment. The house centipede can deliver a mild bite if handled. Millipedes are slow-moving detritivores with two pairs of legs per segment. They do not bite but produce defensive secretions that cause skin irritation in some people.
Treatment Approach in Seattle
Effective control requires both chemical treatment and environmental modification. Perimeter spray reduces the population entering the structure, while moisture and harborage reduction addresses the conditions sustaining the population.