Sowbugs and pillbugs are small land crustaceans that live in damp soil, mulch, and crawl spaces. They wander indoors along moist ground level and, while harmless, signal excess moisture around Whidbey and Fidalgo foundations.
How to identify sowbugs and pillbugs
About 1/4 to 1/2 inch, gray, oval, with a segmented, armored back. Pillbugs roll into a tight ball when disturbed; sowbugs cannot and have two small tail projections.
Behavior & season on Whidbey & Fidalgo
They need moisture and feed on decaying organic matter in mulch, leaf litter, and damp soil. They stray indoors at ground level, especially where crawl spaces and foundations stay wet.
Why sowbugs and pillbugs are a problem
They do not bite, damage structures, or contaminate food, and cannot survive long indoors. Their appearance is a reliable sign of damp conditions and organic debris against the foundation.
Signs of sowbugs and pillbugs activity
- Gray armored bugs at floor level near doors and foundations
- Some rolling into a ball when touched
- Concentrations in damp mulch and leaf litter
- Indoor sightings in crawl spaces and low rooms
How Salty Dog treats sowbugs and pillbugs
We treat the moist perimeter harborage and advise on reducing ground-level moisture and debris so they stop wandering inside. Learn more about our Outdoor Pest Control service, or browse the full Pest Library.
Reviewed by Matthew — Salty Dog Pest Control. WSDA-licensed structural pest applicator (License #101709). Veteran- and family-owned, serving Whidbey Island, Fidalgo Island, and west Skagit County.
Frequently asked questions
Are sowbugs and pillbugs insects?
No — they are land crustaceans, more closely related to crabs. They need damp conditions and cannot survive long indoors.
How do I keep them out?
Reduce moisture and organic debris against the foundation. Dry conditions at ground level are the best deterrent.
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