Napa 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 Napa 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.
How to Tell Centipedes and Millipedes Apart
Centipedes move fast — one pair of legs per body segment, predatory, and capable of a mild bite if directly handled. The house centipede is the most common indoor species and is attracted by the insects it hunts. Millipedes move slowly, coil when disturbed, have two pairs of legs per segment, and feed on decaying matter rather than other insects. They do not bite but produce defensive secretions that can irritate skin and eyes.
Treatment Approach in Napa
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.