Common striped woodlouse (Philoscia muscorum)

GenusPhiloscia (1)
SizeLength: 11 mm (2)

Common and widespread throughout Britain (1).

Woodlice are not insects, but are crustaceans; more closely related to crabs and shrimps than insects. The body is divided into three main regions, the head, the thorax (known in woodlice as the ‘pereion’), and the abdomen (‘pleon’) (3). This species is brownish in colour and mottled with pale patches (4) and, as the name suggests, a clear dark stripe along the back (2).

This woodlouse is very common and widespread in Britain (2).

Found in a wide variety of habitats (1)

Woodlice feed on dead organic matter, which they detect by means of taste and smell (3). The common woodlouse is gregarious, and typically spends the day concealed beneath stones, logs and other objects. When threatened, this species defends itself by clamping down onto the surface; the feet can grip the substrate very tightly, and this woodlouse is able to cling on tenaciously (3).

Mating tends to take place at night, and is very rarely observed for this reason. When a male finds a receptive female, he climbs onto her back and drums her with his front legs whilst ‘licking’ her head with his mouthparts. He moves to one side of the female, bending his body beneath hers, and transfers sperm to one of the female’s genital openings. He then moves to the other side and transfers sperm to the remaining genital opening (3). During the breeding season, reproductive females develop a ‘brood pouch’, which consists of overlapping leaf-like structures known as ‘oostegites’, which form a false floor below the body. The fertilised eggs pass into this fluid-filled chamber and the young crawl out of the brood pouch when they are fully developed. They undergo a series of moults before reaching maturity, growing at each stage; the stages between these moults are known as ‘stadia’, and are generally similar in structure and appearance. Mature woodlice continue to moult; prior to moulting, the calcium contained in the old cuticle is removed and stored as conspicuous white blotches, these blotches disappear after moulting as the calcium is used to reinforce the new cuticle (3). The rear part of the body moults a few days before the front half, and occasionally woodlice may be seen with half a pinkish body and half a ‘usual’ grey body for this reason (5). The discarded cuticle is frequently eaten by the newly moulted woodlouse (2).

Not threatened at present.

No conservation action has been targeted at this species.

For more on invertebrates and their conservation see Buglife, the Invertebrate Conservation Trust at:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. NBN Species Dictionary (Jan 2003):
  2. Woodlice- Natural History Museum (March 2004):
  3. Sutton, S. L. (1972) Invertebrate types: woodlice. Ginn & Company Ltd., London.
  4. The pied piper (March 2004):
  5. Woodlice online (March 2003):