Woodlice, also known as slaters and pillbugs, are terrestrial crustaceans. Their soft bodies are covered on the upper surface with a hard segmented shell, which is often grey but may be pinkish-brown, white, or mottled with white or yellow markings. Woodlice have seven pairs of legs and relatively long and distinct antennae. Pillbug species of woodlice, such as Armadillidium species, curl up into a ball when threatened. The pill millipede, Glomeris marginata, behaves in a similar way and makes a convincing imitation of a pill-type of woodlouse. The pill millipede, however, has short antennae and 17-19 pairs of legs.
The largest British woodlouse is the sea slater, Ligia oceanica, which is 30mm long but the adults of most other species are 2-10mm.
Some species are found throughout Britain but some species are confined to coastal or southern areas.
There are 37 species of woodlice in Britain. Some are widespread but some have restricted distributions.
Woodlice need damp dark places to hide in during the day. They can be abundant in leaf litter, compost heaps, grassland, woodland and gardens.
Where to find them in the garden
In compost heaps and other accumulations of dead plant material, under stones, logs and pots. A small white woodlouse, Platyarthrus hoffmannseggi, lives in ant nests.
Role in the garden
Woodlice occasionally nibble at seedlings and other soft plant growth but they mostly feed on dead decaying plant material and the associated fungal growth. They help to recycle plant nutrients and are not significant garden pests.