Common rough woodlouse vs Common shiny woodlouse
These two are easy to mix up. Here's how to tell a common rough woodlouse from a common shiny woodlouse, and whether either one bites or stings.
Common rough woodlouse
Porcellio scaber
Common shiny woodlouse
Oniscus asellus
≠The key differences
Porcellio scaber has a rough, textured dorsal surface and tubercles; O. asellus is smoother and shinier.
⚖︎Side by side
| Common rough woodlouse | Common shiny woodlouse | |
|---|---|---|
| To humans | Non-toxic | Non-toxic |
| Size | 10-18 mm long | 8-15 mm long |
| Colours | Grey, Brown, Mottled grey-brown | Grey, Brown, Pale cream (legs/antennae) |
| Family | Porcellionidae | Oniscidae |
| Habitat | Moist, shaded microhabitats: under logs, stones, leaf litter, bark, garden mulch, compost heaps, cellars and damp basements | Moist, shaded microhabitats: under logs, stones, leaf litter, compost, tree bark, and inside damp basements or cellars. |
| Range | Native to Europe and now cosmopolitan through accidental human-assisted spread; found in temperate regions worldwide | Native to Europe; widely introduced across temperate regions including North America, New Zealand and elsewhere. |
| Active | Primarily nocturnal and active year-round in mild climates; activity reduced in very cold or dry conditions | Year-round in mild climates; most active at night and after rain |
| Pest? | No | No |
🔍How to spot a common rough woodlouse
- 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
🔍How to spot a common shiny woodlouse
- Smooth, shiny dorsal plates and overall glossy appearance compared with rougher-bodied species
- Size 8-15 mm, flattened oval body with 7 visible segments and rear uropods
- Cannot roll into a tight ball (unlike Armadillidium species)
- Prefers damp shaded places; often found under logs, stones and leaf litter
?Frequently asked questions
What is the difference between a common rough woodlouse and a common shiny woodlouse?
Porcellio scaber has a rough, textured dorsal surface and tubercles; O. asellus is smoother and shinier.
Is a common rough woodlouse or a common shiny woodlouse more dangerous?
Common rough woodlouse: Non-toxic. Common shiny woodlouse: Non-toxic. Porcellio scaber is harmless to people. Harmless to people.
Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.