Woodlice: How to identify and sustainably reduce these little grey crawlers in damp areas

What are woodlice?

Woodlice belong to the Isopoda (terrestrial crustaceans). They require moisture, because they breathe through a kind of "gill" and therefore must not dry out. They are important decomposers in the garden. In living spaces, their presence is usually an indication that there is excess moisture or a damp hiding spot somewhere.

How to identify woodlice

• small, grey to brownish animals with a clearly segmented shell
• move rather slowly and hide during the day
• frequently found under flower pots, mats, cardboard boxes, in cellars, or bathrooms
• when disturbed, some species roll into a ball (pill bugs)

Where do woodlice typically appear?

• Cellar (floors, walls, storage areas)
• Bathroom (joints, behind furniture, in case of poor ventilation)
• Kitchen (under the sink, near leaking connections)
• Patio/balcony (door thresholds, damp mats)

Why do they appear?

• constantly high humidity or damp surfaces
• leaks (water pipes, drains, silicone joints)
• damp storage (cardboard, textiles, wood)
• direct access from outside (door gaps, cellar windows, light wells)

What to do about woodlice in the house? (natural & sensible)

1. Reduce moisture

• regular shock ventilation (especially in cellars/bathrooms)
• use dehumidifiers if necessary
• avoid condensation (keep furniture away from exterior walls)

2. Remove hiding spots

• dispose of or dry out damp cardboard/mats
• keep areas under pots/shelves clean and dry

3. Check entry points

• seal gaps (door thresholds, cellar windows, light wells)
• inspect joints and connections

Woodlice in the garden – often useful

In the garden, woodlice are mostly helpful: they decompose dead plant material and improve the soil. They rarely become a problem – usually only when their population density is very high and they target tender seedlings. Indoors, however, their presence is almost always a signal of moisture.