Woodlice
What are they?
Also known as pillbugs, sowbugs or roly polys, these creatures are land-living members of the crustaceans - and therefore more closely related to shrimps than they are to insects. They still breathe through gill-like structures on the underside of the abdomen and need to be in moist habitats to assist breathing. They have seven pairs of legs and two pairs of antennae - features that they share with aquatic crustaceans. Females carry egg packets in pouches until they hatch and the young look like smaller versions of the adults. They grow slowly but may live up to two years. Woodlice are abundant creatures of damp areas in woodland, gardens and around homes and may easily be found in good number by lifting up any solid object that may have damp soil or leaf litter underneath.
Identification
Woodlice are easily told from other invertebrates by their resemblance to tiny armadillos. Our two commonest species are introduced from Europe and easily told apart. However, some smaller native species can be difficult to identify without at least a powerful hand lens. Check for the presence or absence of two small 'tails' at the back end, whether they can roll into a ball, and check for markings on the body sections.
European Woodlouse Oniscus asellus
(Sowbug) Introduced from Europe and by far our commonest species, especially in urban areas.
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Pill Woodlouse Armadillidium vulgare
(Pillbug) Introduced from Europe. A common species, told by its shiny, blue-gray color and its ability to roll into a ball of disturbed.
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