Common Shiny Woodlouse

The common woodlouse is the most widespread species of woodlouse in the British Isles, both geographically and ecologically, being one of the "most pervasive" of Britain's wildlife. It is adapted equally well to northern areas as to southern ones, and has been recorded in every vice-county of England, Scotland, Wales, and Ireland. It is less common in the Mediterranean Basin, but is widespread in Northern and Western Europe, from Portugal to Sweden as far east as Ukraine, as well as in the Azores and Madeira; it has also been widely introduced in the Americas, predominantly in Mexico and in the United States, east of the Mississippi River and west of the Rocky Mountains. According to the British Myriapod and Isopod Group, Oniscus asellus, along with Porcellio scaber, "represents the archetypal 'woodlouse' familiar to the general public". As of April 2025, Oniscus asellus is the third-most observed species of woodlouse in the world in the citizen science website iNaturalist, after Porcellio scaber and Armadillidium vulgare.

The common woodlouse occurs in a wide range of habitats, including some with little available calcium, but not dry ones. The species is found both inland and in coastal areas, chiefly in the countryside, but the species is also a successful synanthrope, and is frequent inhabitant of human spaces such as greenhouses, gardens, and parks. The common woodlouse is found in waste grounds, open woodlands, forests, and gardens, as well as in grasslands, scrub, and around buildings. The plurality (22%) of records examined in one study were found on road verges, although it has also been collected from cliff faces and quarries. It most commonly dwells in moist environments under rocks or dead wood, but has also been recorded from litter, human constructions, and garbage. It is especially prevalent in rotting wood, a tendency which allows it to inhabit areas otherwise unfriendly to woodlice such as moorlands. Linnaeus in 1758 noted it was found in houses, but also rotting wood, hibernacula, and walls. Woodlice may be predated on by toads and newts. According to Stefan Gates, they have a sweet meat with taste similar to crab or shrimp, and considerable umami flavour.

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