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Quick answer: Pillbugs (roly-polies) and sowbugs are small, segmented crustaceans, not insects, that live in damp soil, mulch, and leaf litter and wander indoors along the foundation. They are harmless and do not damage the home, but they signal excess moisture. Control is about drying out the perimeter, removing damp harborage, and sealing entry points.
What do pillbugs and sowbugs look like?
Pillbugs and sowbugs are small, gray, segmented land crustaceans — relatives of crabs and shrimp, not insects — with an armored, plated back. Pillbugs can roll into a tight ball (the roly-poly) and lack tail appendages; sowbugs cannot roll up and have two small tail-like projections.
Signs of pillbugs and sowbugs
You will find them under mulch, stones, logs, and debris outdoors, and wandering into basements, garages, and along door thresholds. Indoors they are usually found dead or dying because the air is too dry for them.
Why they appear
These crustaceans breathe through gill-like structures and need constant moisture. Their presence indoors is a reliable moisture signal — damp mulch, poor drainage, or wet soil against the foundation. They feed on decaying organic matter and do not harm the home.
How to control pillbugs and sowbugs
Control is moisture and harborage reduction around the perimeter: move mulch, leaves, and debris away from the foundation, improve drainage and grading so water flows away from the house, fix damp areas in basements and crawlspaces, and seal entry points such as door sweeps, thresholds, and foundation gaps. Drying the perimeter removes what supports them.
When to call a professional
Persistent pillbugs or sowbugs indoors point to a moisture or drainage issue. A professional can identify the source, treat perimeter harborage, and recommend the exclusion and moisture fixes that keep them out.
A Brooklyn-based, NYSDEC-registered company (Reg. #15140) led by Jorge Bedoya, an Associate Certified Entomologist (ACE). For pests in your home or building, NYE provides IPM-based, low-exposure control matched to the exact pest and verified with a follow-up. ACE-led work comes with a client portal of service reports and photos, fully bilingual service, and no long-term contract.
Pillbug and Sowbug FAQ
What is the difference between pillbugs and sowbugs?
Both are segmented, gray, land crustaceans. Pillbugs can roll into a tight ball when disturbed (roly-poly) and have no tail-like appendages; sowbugs cannot roll up and have two small tail-like projections.
Are pillbugs and sowbugs harmful?
No. They do not bite, sting, spread disease, or damage the structure. They feed on decaying organic matter and are mainly a nuisance when they wander indoors.
How do you get rid of pillbugs and sowbugs?
Reduce moisture around the foundation: move mulch, leaves, and debris away from the house, improve drainage and grading, fix damp areas, and seal entry points like door thresholds and foundation gaps.
Why are they in my basement or garage?
They need constant moisture and wander in from damp soil and mulch through gaps, gathering in basements, garages, and along thresholds. They usually dry out and die indoors because it is too dry for them.
Where do pillbugs and sowbugs live?
In damp, dark places: under mulch, leaf litter, stones, logs, and debris, and in moist soil against the foundation.
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