Common rough woodlouse
Porcellio scaber · Woodlice
A common, non-stinging terrestrial crustacean that eats decaying plant matter and prefers damp, sheltered places around houses and gardens.
!Is the common rough woodlouse dangerous?
No. Porcellio scaber is harmless to people. It does not sting, bite or deliver venom. Handling may leave a faint smell or a small amount of dirt; wash hands after handling. They are not known to transmit human disease.
Pets
Generally harmless to cats and dogs. Pets might eat them out of curiosity; the woodlouse is not poisonous, though eating many could upset a pet's stomach. Some pets may avoid them because of their texture or smell.
📖Overview
Porcellio scaber is a widespread species of woodlouse (terrestrial isopod) often found under logs, stones, leaf litter and in damp basements or garden mulch. It is a detritivore that helps break down dead plant material and recycle nutrients. Adults are slow-moving, nocturnal and avoid bright, dry conditions.
They are not insects but crustaceans adapted to life on land; females brood eggs and young in a pouch called a marsupium. Porcellio scaber is tolerant of a range of habitats and has been introduced globally from its native European range.
🔍How to identify a common rough woodlouse
Adults are roughly oval, flattened top-to-bottom, with a distinctly rough, bumpy texture on the dorsal plates (pereonites). Colour ranges from grey to brown and sometimes mottled. Body length is typically about 10-18 mm. Unlike pillbugs (Armadillidium species) this species cannot roll into a tight ball and its uropods (rear appendages) project beyond the last body segment.
- Rough, bumpy dorsal plates (uneven texture) rather than smooth
- Cannot roll into a tight ball; body remains flattened when disturbed
- Adult length about 10-18 mm and generally grey to brown in colour
- Uropods (small tail-like appendages) extend beyond the rear margin of the body
Lookalikes
Common pillbug Armadillidium vulgare
Can roll into a tight ball (conglobate) and has smoother, more rounded plates; Porcellio scaber cannot fully roll up.
Smooth woodlouse Porcellio laevis
Smoother and shinier dorsal plates and often larger; P. scaber has a distinctly rough texture.
↻Life cycle
Egg
Eggs are retained and develop inside a brood pouch (marsupium) on the female until the young hatch.
Juvenile (manca)
Young emerge from the marsupium as small, pale mancas that resemble adults but have only six pairs of legs; they gain the seventh pair and grow through several moults.
Adult
Sexually mature after several moults; adults continue to moult periodically and can live 1-3 years.
🍃Diet and predators
Young eat
Decaying plant matter, detritus and fungal material similar to adults
Adults eat
Primarily decaying leaves, wood, mulch and fungi; occasionally tender seedlings or soft fruit if abundant and other food is scarce
Predators of the young
Small predators such as centipedes, spiders, beetles, small amphibians and birds
Predators of adults
Birds, amphibians, small mammals (shrews, hedgehogs), centipedes and predatory ground beetles
🌱Effect on plants and gardens
Feeds on decaying plant material and fungi; usually does not damage healthy living plants. In very large numbers and in very damp, young plantings or seed beds, they can nibble tender seedlings or fruit, but this is uncommon.
📍Where and when to find it
Look under stones, logs, flowerpot saucers, compost heaps, mulch, bark and in damp basements or cellars. Juveniles are found alongside adults in the same sheltered, moist microhabitats.
Best time
Night-time or after rain; active year-round in temperate regions but most visible during wet periods
Observation tips
Turn over damp refuges slowly and photograph from a low angle. Use a torch at night to spot them moving on the surface of mulch or leaf litter.
✨Fun facts
- Woodlice are terrestrial crustaceans, more closely related to shrimp than to insects.
- Females brood their young in a pouch called a marsupium, where eggs develop in water retained by the mother.
- They breathe using structures called pleopodal lungs or gills on the underside, which is why they need moist habitats.
?Frequently asked questions
Are rough woodlice dangerous?
No. Porcellio scaber are harmless to people and pets; they do not sting or transmit disease.
Do rough woodlice bite?
No. Woodlice have small mouthparts for chewing decaying plant matter and cannot bite people.
Why are there woodlice in my house?
They are attracted to damp, cool, dark places such as basements, cellars, bathrooms, or areas with damp wood or mulch. Moisture and easy shelter draw them inside.
How do I get rid of woodlice?
Reduce moisture and shelter: fix leaks, ventilate damp areas, seal entry points, remove leaf litter and wood debris near the foundation. Sticky traps or a shallow dish with wet folded cardboard can catch them for removal. Chemical control is rarely necessary.
Do woodlice damage my plants or house?
They mainly feed on decaying matter and help decomposition. They rarely damage healthy plants; they do not eat wood used in sound structural timber like termites do.
📷Photos of the common rough woodlouse
More woodlice & pill bugs
This guide was written with AI assistance and fact-checked, last updated 2026-10-10. Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions. More about the common rough woodlouse: iNaturalist, Wikipedia.