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Woodlouse — species photo
Daniel Brady · NH-Licensed Pesticide Applicator · License #782664

How to Get Rid of Woodlice

DIY-friendly
To get rid of woodlice, fix the moisture problem that's drawing them indoors — ventilate crawl spaces and basements, fix leaks, run a dehumidifier, and move mulch, leaf litter, and firewood away from the foundation — then seal foundation gaps and sweep or vacuum up any strays. Woodlice are harmless land crustaceans (not insects) that need dampness to survive; without it, indoor strays die within a day or two on their own. Spraying insecticide without fixing the underlying dampness fails, because the moisture source, not the woodlice themselves, is the actual problem. A large number indoors is really a sign of a large, healthy outdoor population just outside your walls.

At a glance

  • Difficulty: Beginner
  • Time: A weekend to address moisture and mulch/debris near the foundation; ongoing sweeping of strays
  • Cost: Low — a dehumidifier, caulk, and a rake
  • Success: High once the moisture source is fixed — woodlice can't establish indoors without dampness
The honest answer

Can you DIY Woodlouse?

The verdict on Woodlouse DIY

DIY-friendlyBeginner

A beginner-friendly DIY — fix the dampness and woodlice leave on their own.

"Woodlouse" is a common name (used especially in Europe) for terrestrial isopods — land crustaceans, not insects — that breathe through gill-like structures and need moisture to survive. They're harmless decomposers that wander indoors from damp areas and die within a day or two without it. There's no infestation to eliminate with pesticide; the fix is drying out and blocking the moisture and harborage that drew them in.

The playbook

The 5 DIY methods — honestly graded

Every approach graded for this species, in IPM order — prevention first, chemistry late. Pick a method to see how it works, the steps, and what it actually takes.

Prevention / Exclusion

Works well

Moisture and harborage reduction is the real fix — this is the dominant lever for this species, not pesticide.

Woodlice can only survive where humidity is high enough to keep their gill-like respiratory structures moist. Removing damp harborage and sealing entry points removes both their habitat and their route indoors.

Best for: Solving the root cause, not just the symptom

  1. Cut the moisture

    Ventilate crawl spaces and basements, fix leaking pipes and gutters, and run a dehumidifier in persistently damp areas.

    Tip
    Target basement/crawl-space relative humidity below roughly 50%.

  2. Move harborage off the foundation

    Pull mulch, leaf litter, and firewood at least several inches away from the foundation, and seal foundation cracks and gaps.

Tools & materials

DehumidifierCaulkRake
Before you start
Treating the bugs without fixing the dampness means they keep coming back.
Reality check

Why DIY falls short here

Not scare tactics — the specific, proportionate reasons a home attempt can stall for this species.

Treating the bug, not the dampness

Sprays or repeated sweeping fail to stop the problem while the moisture source that drew woodlice in the first place remains unaddressed.

Ignoring the outdoor population

Many woodlice indoors signals a large, healthy damp population living just outside your walls — indoor cleanup alone won't shrink that source.

Mulch touching the foundation

Mulch or leaf litter piled against the house acts as a bridge that funnels woodlice directly to foundation gaps, undoing sealing efforts.

Straight talk

How risky is it, really?

An honest read — most nuisance species are genuinely low risk, and we say so.

Low risk

Woodlice are harmless — they don't bite, sting, spread disease, or damage the structure. Indoors, they're best understood as a moisture indicator, not a threat to your health or home.

  • Bite, sting, or disease transmissionRare

    Not documented — woodlice have no mouthparts capable of biting people and carry no known disease risk

    University of Florida IFAS Extension

  • Structural or property damageRare

    They feed on decaying organic matter, not sound wood or building materials

    Missouri Department of Conservation

  • Large indoor numbers signaling a moisture problemOccasional

    A practical flag worth investigating (leaks, poor drainage, crawl-space humidity), even though the woodlice themselves are harmless

    University of Florida IFAS Extension

When to call a pro

Can't Find the Moisture Source?

A hidden leak or drainage problem can be hard to track down on your own. Anchor Pest Services offers a full moisture and exclusion assessment across southern and central New Hampshire. Family-owned since 2017, NH license #782664.

Call a pro when…

  • Woodlice persist after your own moisture and exclusion fixes
  • You suspect a hidden leak or drainage problem you can't locate
  • You want a full building-envelope moisture and exclusion assessment

General Pest Control

You rarely need a pro for woodlice — this is a moisture-and-mulch job. The exception is a persistent, hard-to-locate moisture source (a hidden leak, poor grading, or crawl-space humidity you can't resolve yourself).

Get a Free inspection(603) 785-0118

Keep them out

  • Keep basement/crawl-space humidity below roughly 50%
  • Move mulch, leaf litter, and firewood away from the foundation
  • Fix leaks and improve drainage away from the house
New Hampshire context

Woodlice in New Hampshire

Woodlice, sowbugs, and pillbugs are closely related terrestrial isopods and common names overlap regionally — "woodlouse" is the broader umbrella term. In New Hampshire's humid basements and crawl spaces, they're most active in the wetter shoulder seasons (spring and fall) when outdoor moisture is high, wandering in from damp mulch beds and foundation soil.

Peak season

Spring and fall, during high-moisture periods

First-frost anchor

Manchester first hard frost ~Oct 19 (50%) / Oct 29 (80%), NOAA 1991–2020

Before you treat

Make sure it's a Woodlouse

Two quick detours worth taking — confirm the ID, then learn what drew it in so it doesn't come back.

Not sure it's this?

Identify Woodlouse in the Pest Library

Why is it here?

What actually attracts Woodlouse

Common questions

Frequently asked

Sources & further reading(2)
  1. [1]
    University of Florida IFAS Extension — Terrestrial Isopods (IN1099)

    Biology, harmless status, moisture dependency, control recommendations

    extensionverified 2026-07-13
  2. [2]
    Missouri Department of Conservation — Pillbugs and Sowbugs (Land Isopods)

    Species overlap and identification, decomposer role

    govverified 2026-07-13

Written & reviewed by

Verified

Daniel 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.

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Last updated July 2026

More in Household & Occasional Invaders

Other species you can tackle

Same category — the dot shows each one's DIY verdict at a glance (green = friendly, amber = doable with care, red = call a pro).

Professional Pest Control

Can't Find the Moisture Source?

A hidden leak or drainage problem can be hard to track down on your own. Anchor Pest Services offers a full moisture and exclusion assessment across southern and central New Hampshire. Family-owned since 2017, NH license #782664.

Get a Free inspection(603) 785-0118
  • Moisture-source diagnosis
  • NH-licensed applicators (#782664)
  • Free inspection — same-day service across southern NH

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