Porcellio scaber

CRUSTACEA > MALACOSTRACA > ISOPODA > Oniscidea > Crinocheta > Porcellionidae

Porcellio scaber is another large species that can attain a length of up to 17mm. It has a rough, heavily tuberculate, typically uniform slate-grey body with a continuous outline between the pereion and pleon. The head is the same colour as the body with eyes comprised of numerous black ocelli, and the antennal flagella made up of two, rather than three, segments. If the individual can be viewed from the underside it will have two pairs of visible pleopodal lungs.

As well as the normal grey colour, it is not uncommon to find pale and/or variously mottled coloured individuals, some of which may have a pale orange base to the antennae. Any pattern is random, and not regularly spaced longitudinal mottling as found on either the closely related, but comparatively much rarer Painted Woodlouse [Porcellio spinicornis], or the localised Rathke's Woodlouse [Trachelipus rathkii] which has not been recorded in Dorset.

This species can be found almost anywhere including inside houses or out buildings as well as climbing walls and trees. That said, it is more likely to be located at ground level under stones or deadwood. Given the nature of some of these locations it is not surprising to note that it is far more tolerant of dry conditions than some of the other larger woodlice such as Oniscus asellus.

Updated, Sept.26 (v.2)