At a glance
Essentials
- Size
- Reaches a length of between 17 and 20 mm. The range may vary with age, sex and population.
- Distribution
- Native to Central and Western Europe; introduced in North America, South America, South Africa and Australia.
- Habitat
- Inhabits moist soils, leaf litter, under stones or decaying wood.
- Activity
- Feeds primarily on decaying plant matter and associated microorganisms.
- Diet
- Detritivore; consumes decaying leaf litter and fungi/bacteria.
Observation guide
What to look for
- 01
Oval and flattened body, generally dark grey or slate in color, with individual variations.
- 02
Dorsal surface covered by small tubercles.
- 03
Unable to roll into a ball; adopts tonic immobility in the face of threats.
- 04
Pointed telson (caudal plate) at the posterior extremity.
Lighting, age and viewing angle can hide features. If identification affects consumption, handling or conservation, consult specialist sources.
Ecology
Description and characteristics
Porcellio scaber is a species of terrestrial isopod crustacean belonging to the family Porcellionidae. Its body is oval and flattened in shape, with a coloration that varies between grey, brown tones and, on occasion, spotted patterns. Unlike other species of woodlice, it does not possess the ability to roll into a ball for defense, instead adopting a posture of tonic immobility in the presence of predators.
The dorsal surface of its segmented exoskeleton is covered by a series of small tubercles, a feature that gives it its common name in English (rough woodlouse). The abdomen, composed of six segments, presents on its ventral side two whitish pseudo-lungs that allow it to breathe atmospheric air. Lacking an impermeable waxy cuticle, it loses water by diffusion through its exoskeleton, which limits its survival to environments with adequate humidity levels.