Woodlice in the house: causes, signs and fixes

Written by Avon Pest ControlFirst published 27 March 2026Updated 9 November 2026

Woodlice are one of the most common creatures people find indoors, usually in bathrooms, kitchens, hallways and ground-floor rooms. They are harmless, but they are also a good damp detector: if you keep finding them, something in or around the house is wetter than it should be.

The short version

• Woodlice do not bite, sting, spread disease or damage sound timber or furniture.
• They need moisture to survive, so most die within a day or two in a dry, heated room.
• Regular sightings point to damp, poor ventilation or gaps at ground level. Those are the things to fix.

Why woodlice come inside

Woodlice are crustaceans rather than insects, and they lose water through their bodies quickly. Outdoors they live under stones, logs, leaf litter, compost and rotting wood, feeding on decaying plant material. They come indoors when the conditions around the house, or inside it, match what they need.

The usual reasons are:

• Damp walls or floors, including rising or penetrating damp and condensation.
• Poor ventilation in bathrooms, kitchens and cupboards on outside walls.
• Gaps under doors, cracked brickwork, unmeshed air bricks and gaps around pipes.
• Rotting timber, decking, log piles or garden debris against the walls.
• Heavy rain, which drives them out of waterlogged ground and into shelter.

Indoors they wander along skirting boards in search of moisture and often end up stranded in baths and sinks. They do not set up home in dry rooms. If they are breeding inside, it is because a spot is damp enough to let them, such as a wet subfloor, a leaking shower tray or rotten skirting.

Are woodlice dangerous?

No. They are no risk to people or pets, and they feed on material that is already decaying rather than on sound wood or food. The thing to take seriously is what their presence suggests. Damp that is left alone leads to mould, timber decay and damaged plaster, and those are far more expensive problems than the woodlice.

Signs you may have a woodlice problem

• Live or dead woodlice on floors and windowsills, or in sinks and baths.
• More of them after wet weather.
• Damp patches, peeling paint or a musty smell near where you find them.
• Woodlice gathering at external doors, thresholds or along one particular wall.

One or two now and then is normal, especially in older houses. Several most days, or always in the same room, means there is a reason they are getting in and surviving.

Why DIY methods rarely solve the problem

Sweeping or vacuuming them up deals with what you can see, and insecticide sprays indoors do the same. Neither changes the damp that brought them in or the gap they used, so more arrive. Control comes from making the house drier and harder to get into:

• Reduce moisture indoors.
• Seal gaps at ground level.
• Improve ventilation.
• Remove the shelter they live in outside, next to the walls.

Preventing woodlice in your home

• Ventilate. Use extractor fans in bathrooms and kitchens and leave them running for a while after a shower or cooking. Open trickle vents on windows.
• Fix leaks and damp promptly. Check under sinks, around shower trays and behind washing machines.
• Clear the wall line. Keep soil, leaves, compost and plant pots away from external walls, and make sure soil is not piled above the damp-proof course.
• Store firewood away from the house, off the ground.
• Seal the gaps. Fit brush strips to external doors, seal around pipes and cables, and fit fine mesh over air bricks without blocking them. Air bricks ventilate the floor and must stay open.
• Let air into enclosed spaces such as under-stairs cupboards and the backs of wardrobes on cold outside walls.

When to call us, and when to call someone else

If the woodlice keep coming after you have dealt with ventilation and the obvious gaps, we can trace where they are getting in and recommend proofing for those points. Treatment is rarely the answer for woodlice and we will not sell you one you do not need.

If you can see or smell damp, the right person is often a builder, roofer, plumber or independent damp surveyor rather than a pest controller. Sorting the moisture is what stops the woodlice, and we will tell you if that is where your money is better spent.

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