Pillbugs & Sowbugs in the San Gabriel Valley
Pillbugs and sowbugs are harmless moisture-lovers that wander in from damp soil and mulch. Here's how to identify them and why they're really a moisture signal.
- Grey, oval, armored segments (like tiny armadillos)
- Pillbugs roll into a tight ball; sowbugs don't
- Seven pairs of legs; not insects (they're crustaceans)
- Found in damp spots: soil, mulch, under pots
- Harmless — don't bite, sting or damage the home
What they look like
Pillbugs and sowbugs are the small, grey, armored crawlers you find under flowerpots and in damp garages — often called roly-polies. They're oval, segmented and about a third of an inch, with seven pairs of legs. The easy tell: pillbugs roll into a tight ball when disturbed, while sowbugs (which have two little tail-like points) can't roll and just scurry.
They're not actually insects at all — they're land crustaceans, more closely related to shrimp and crabs, which is why they need constant moisture to breathe and survive.
Pillbugs & Sowbugs fast facts
| Detail | |
|---|---|
| Looks like | Grey, oval, armored; rolls into a ball (pillbug) |
| Where found | Damp soil, mulch, under pots, garages |
| What they do | Eat decaying plant matter; harmless indoors |
| Active when | Night; damp weather and after watering |
| Concern level | Nuisance only — no bites or damage |
Where they live
Pillbugs and sowbugs live outdoors in the moist layer under mulch, leaf litter, stones, logs, flowerpots and along the damp soil at the foundation. They feed on decaying plant matter and are actually helpful in the garden, breaking down organic material.
They only come indoors by accident, usually into garages, ground-floor bathrooms, laundry rooms and crawlspaces — and only where it's damp. Because they dry out quickly, any that wander onto a dry floor usually die within a day, which is why you often find them belly-up.
Signs of a problem
The “problem” is almost always just numbers wandering in after rain or heavy watering, especially where mulch or soil sits right against the house. Finding several in the garage or a damp bathroom, alive or curled up dead, is the usual sign.
Large numbers indoors are really a message about moisture: a leak, poor drainage, over-watered beds against the foundation, or mulch piled against the siding. The pillbugs are a symptom, not the real issue.
How they are controlled
Because they're a moisture pest, the fix is drying out the edge of the house: pull mulch and heavy plantings back from the foundation, fix drainage and leaks so water doesn't pool, and seal gaps under doors and around the garage where they slip in. Sweep up the ones indoors — they can't survive inside for long anyway.
For repeated invasions, a treatment of the perimeter and the damp harborage along the foundation keeps the numbers down. They often share those damp zones with earwigs and crickets, so the same moisture fixes help with all three. Ask for a free quote if they keep marching in.
Related Pests
Quick Answers
Quick Answers.
Are pillbugs and sowbugs harmful?
No. They don't bite, sting, carry disease or damage your home or furnishings. They feed only on decaying plant matter, so indoors they're purely a nuisance — and they usually dry out and die within a day on a dry floor.
What's the difference between a pillbug and a sowbug?
Both are grey, armored and oval, but a pillbug rolls into a tight ball when disturbed and a sowbug can't — the sowbug also has two small tail-like points at the rear. Their habits, and the way you handle them, are otherwise the same.
Why do I keep finding them in my garage or bathroom?
Those are the damp, ground-level spots they wander into, usually after rain or watering. Steady numbers indoors mean there's moisture drawing them — mulch or wet soil against the house, a leak, or poor drainage near that room.
Are pillbugs a sign of a bigger problem?
Not a pest problem, but often a moisture one. Lots of pillbugs indoors points to dampness against the foundation — over-watered beds, drainage issues or a leak — that can also invite earwigs, crickets and even rot over time. The pillbugs are an early warning.
How do I keep pillbugs out?
Dry out the perimeter: pull mulch and dense plants back from the walls, fix drainage and leaks, and seal gaps under doors and around the garage. A drier band of soil around the house is the single best deterrent.
Do I need pest control for pillbugs?
Usually not — fixing moisture and sealing entry points handles most cases. If they keep invading in large numbers despite that, a perimeter treatment of their damp harborage stops it, and it's worth checking the moisture source while we're at it.
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