Pillbugs (Roly-Polies) in New Hampshire — ID & Control
Also called roly-poly · woodlouse · armadillo bug
The pillbug — also called roly-poly or woodlouse — is not an insect but a harmless land crustacean (isopod) that breathes through gills and rolls into a perfect ball when disturbed. It wanders indoors from damp soil and mulch, but can't survive dry interiors and is never a true infestation. Fix the damp foundation perimeter and it stops.
- What it is
- Crustacean (isopod), not an insect
- UF/IFAS
- Defining trick
- Rolls into a complete sphere when disturbed
- Missouri Dept. of Conservation
- Size
- ~¼–½ in (to ~18 mm)
- Missouri Dept. of Conservation; Encyclopedia.com
- Legs
- Seven pairs (14 legs)
- University of Kentucky Entomology
- Dangerous?
- No — harmless decomposer
- University of Kentucky Entomology
- Indoor survival
- Dies — dries out without moisture
- University of Kentucky Entomology
It's not a bug — it's a crustacean that rolls
The pillbug — better known as the roly-poly — is not an insect at all. It is a land crustacean (isopod) more closely related to crabs and shrimp than to any beetle or ant. It breathes through gill-like structures that require moisture to function, and its signature move is rolling into a tight, perfect sphere when disturbed — the trait that gives it the name roly-poly. It is completely harmless: it does not bite, sting, or carry disease, and it is a beneficial decomposer of decaying plant matter in the garden.
Pillbugs live in damp soil, mulch, and leaf litter, and only wander indoors from the perimeter. Indoors, they cannot survive — they dry out and die — so a pillbug inside the house is a moisture symptom, never a true infestation. The durable fix is drying the foundation perimeter: pull mulch back at least six inches from the foundation wall, fix grading and drainage so water flows away from the house, and seal door sweeps and foundation gaps. The fastest disambiguation from its cousin: a pillbug rolls into a perfect sphere when touched; a sowbug stays flat and has two short rear 'tail-points.'
How to identify a pillbug
The pillbug's defining feature is unmistakable: it rolls into a complete, tight sphere when disturbed. No other common NH pest does this. Secondary confirms are the rounded convex armored back, seven pairs of legs (not six), and its consistent presence in damp spots under mulch, pots, and leaf litter.
Pillbug
- Scientific name
- Armadillidium vulgare
- Family
- Armadillidiidae
- Size
- ~¼–½ in (to ~18 mm)
- Coloration
- Dark gray, sometimes mottled; smooth convex armored plates
- Habitat
- Damp soil, under leaves, rocks, logs, and mulch; garden beds and foundation perimeters
- Active season
- Spring through fall, nocturnal
- Diet
- Decaying plant matter (detritivore); beneficial decomposer
- Reproduction
- Females carry eggs and young in a brood pouch (marsupium) under the body
- Lifespan
- ~2–3 years
Introduced from Europe; now cosmopolitan worldwide. Common throughout New Hampshire.
The tells — key ID features
- Rolls into a complete sphere when disturbed — the single most recognizable tell, shared by no other common NH pest.
- Rounded, convex armored back of overlapping plates — the 'armadillo bug' silhouette.
- Seven pairs of legs (14 total) — not six, confirming it is not an insect.
- Two pairs of antennae (one pair reduced and small).
- ~¼–½ inch, dark gray, no protruding rear tails (unlike sowbugs).
- Always found in damp spots — under mulch, pots, logs, or near a damp foundation.
Size, to scale
~¼–½ in (to ~18 mm)
About the size of a pencil eraser when uncurled; forms a ball roughly the diameter of a garden pea when rolled.
Sowbug
How to tell — Sowbugs cannot roll into a ball and have two short pointed 'tails' (uropods) at the rear. If the bug stays flat when disturbed, it is a sowbug, not a pillbug.
Pill millipede
How to tell — Pill millipedes also roll into a ball but have many more leg pairs and body segments. In New Hampshire they are uncommon; the common roller is the pillbug.
Signs of a problem
Pillbugs announce themselves by their location and behavior more than by any visible damage. These are the signs to look for.
Gray 'armadillo bugs' that curl into a perfect ball when you pick up a pot or lift mulch
What it means — Pillbug harborage in damp perimeter material — a sign the foundation area is consistently moist.
Pillbugs found indoors near damp basement walls, doorways, or crawl-space entries
What it means — Moisture-entry event — they wandered in from a damp perimeter through gaps in the door sweep or foundation.
Many pillbugs in the garden or compost
What it means — Normal and beneficial — they are decomposers in healthy moist soil, not a problem outdoors.
Dead or desiccated pillbugs found inside
What it means — They entered seeking moisture but could not survive the drier indoor environment — confirms moisture entry from the perimeter.
The real risks, calibrated
Pillbugs are among the most harmless pests that turn up in NH homes. The real concern is what their presence tells you about foundation moisture.
Bite, sting, or disease
Low riskOnset: N/A
Pillbugs do not bite, sting, or carry disease transmissible to people or pets. Zero health risk.
Minor seedling or soft-fruit feeding
Low riskOnset: Outdoors in growing season
Occasional minor feeding on very tender seedlings or soft fruit touching the soil; rarely significant.
Indoor survival
Low riskOnset: Upon entering a dry interior
Pillbugs dry out and die indoors — they cannot breed or establish an indoor infestation.
Foundation-moisture indicator
Low riskOnset: Ongoing presence at perimeter
A perimeter pillbug population signals persistently damp conditions around the foundation — the real issue to address.
DIY — what works, what backfires
The fix for pillbugs is drying the foundation perimeter, not spraying. Here is what actually works.
What actually works
- Pull mulch, leaf litter, and compost back at least 6 inches from the foundation wall to remove damp harborage.
- Fix grading and drainage around the foundation so water flows away from the house rather than pooling against it.
- Seal door sweeps and foundation gaps — these are the entry points from the damp perimeter.
- Sweep or vacuum the occasional indoor wanderer; no treatment needed indoors.
- Let the indoor area dry — pillbugs that wander in cannot survive dry conditions.
What backfires
- Don't treat a pillbug in the basement as an indoor infestation — it cannot breed or establish indoors.
- Don't pile damp mulch, leaf litter, or firewood against the foundation — this is the primary driver.
- Don't spray indoors for pillbugs — the fix is perimeter moisture, not pesticide.
Pillbugs in New Hampshire gardens and homes
Across Manchester, Nashua, Concord, and the wider southern NH service area, pillbugs are a common presence in gardens and around damp, mulched foundations — especially where shrubs, mulch, or leaf litter are piled against the house. They wander indoors during wet spells or when perimeter moisture is high, typically entering through door sweeps and foundation gaps. Indoors, they cannot survive the drier conditions and die — which is why finding dead ones inside is itself a moisture-entry clue.
Peak season
Spring through fall, most active in warm wet weather
You might actually have
- Sowbugs (can't roll; have two rear tail-points — the non-rolling cousin)
- Woodlice (umbrella term covering both pillbugs and sowbugs)
- Springtails (also a moisture indicator — tiny hopping specks)
We serve these communities
- NH-licensed applicator · #782664
- Same-day service
- Family-owned since 2017
Service Area Map
Southern New Hampshire
When to call a pro for pillbugs
If you're finding large numbers of pillbugs pushing into the home despite pulling back mulch and fixing drainage, a licensed technician can address perimeter moisture and exclusion comprehensively — and confirm whether the moisture source is something harder to fix, like foundation seepage.
When to call a pro
- Large recurring populations entering the home despite removing perimeter mulch and leaf litter.
- Suspecting foundation moisture or drainage issues beyond standard grading fixes.
- Persistent indoor sightings through multiple seasons despite perimeter management.
Pull mulch back from the foundation
Keep mulch, decorative stone, and leaf litter at least 6 inches away from the foundation wall year-round. This single change is the most effective pillbug prevention.
Fix grading and drainage
NH homes with flat or inward-sloping grades trap water against the foundation. Re-grading to slope water away and adding downspout extensions removes the moisture pillbugs need.
Seal door sweeps and foundation gaps
Pillbugs enter through the smallest gaps under doors and around foundation penetrations. Replace worn door sweeps and seal gaps with appropriate caulk or foam.
Not sure it's a pillbug?
A licensed NH technician can confirm the species and tell you honestly whether it's a DIY fix or a job for a pro — free inspection, same-day service across Southern New Hampshire.
Frequently asked questions
Sources(6)
- [1]UF/IFAS — Pillbug (EENY630)
crustacean classification, cosmopolitan introduction, beneficial decomposer
extensionverified 2026-06-30 - [2]University of Kentucky Entomology — Sowbugs and Pillbugs
seven leg pairs, gill breathing, indoor survival, no health risk
extensionverified 2026-06-30 - [3]Missouri Dept. of Conservation — Pillbugs and Sowbugs
rolls into a ball description, size, coloration
govverified 2026-06-30 - [4]Animal Diversity Web — Armadillidium vulgare
species profile, reproduction, lifespan
academicverified 2026-06-30 - [5]
- [6]UNH Cooperative Extension — Insect Identification
NH presence and moisture-first guidance
extensionverified 2026-06-30
Written & reviewed by
VerifiedDaniel Brady
NH-Licensed Pesticide Applicator · License #782664 (NHDAMF, RSA 430)
Daniel Brady is the New Hampshire–licensed applicator behind Anchor Pest Services, a family-owned pest control company serving the Manchester area since 2017.
Last updated 2026-06-30
New Hampshire pest control
Dealing with pillbugs in your home?
Anchor Pest Services identifies and handles pillbug problems across southern and central New Hampshire. Family-owned since 2017, NH license #782664.
- NH-licensed applicators (#782664)
- Same-day service · free inspection
- Family-owned since 2017