Swift Woodlouse

P. laevis was first recorded in Britain in the 13th century but it likely originated in North Africa. It has a cosmopolitan distribution, and has been introduced to Australia, including Norfolk Island and Lord Howe Island. The species is also found in North and South America, Western Asia, Japan and some Pacific islands. This species is found under rocks and fallen logs in damp areas, and is otherwise rarely encountered. Records from Ireland and Britain also place them in agricultural areas like gardens, farms, and stables where they can be found in dung and compost piles.

Porcellio laevis is one of several species of isopods known to use "alternating turns" as a defense mechanism, running in a mazelike pattern to confuse or avoid perceived threats. Studies suggest that this behavior, also observed in Armadillidium vulgare, can be reinforced as a learned response, with more "alternating turns" produced by longer and more frequent exposure to predators.