Not necessarily a complete list
Infraorders:
Ligiamorpha
Tylomorpha
Families:
Dubioniscidae
Irmaosidae
Pseudarmadillidae
Scleropactidae

A woodlouse, also known as a pill bug (genus Armadillidium only), armadillo bug, sow bug, slater, ball bug, doodlebug, or roley-poley/roly-poly, is a terrestrial crustacean with a rigid, segmented, calcareous exoskeleton and fourteen jointed limbs. They form the suborder Oniscidea within the order Isopoda, with over 3000 known species.

Woodlice need moisture and so are usually found in damp, dark places, such as under rocks and logs. They are usually nocturnal and are detritivores, feeding only on dead plant matter.

In the United Kingdom there are 37 native or naturalized species ranging in colour and in size (3 to 30mm) of which only five are common: Oniscus asellus (the common shiny woodlouse), Porcellio scaber (the common rough woodlouse), Philoscia muscorum (the common striped woodlouse), Trichoniscus pusillus (the common pygmy woodlouse) and Armadillidium vulgare (the common pill bug).

Some woodlice are able to roll into a ball-like form when threatened by predators, leaving only their armoured back exposed. It is this ability which explains many of the woodlouse's common names.

A female woodlouse will keep fertilised eggs in a patch on the underside of her body until they hatch into small, pink offspring. The mother then appears to be "giving birth" to her offspring.

Linguistics

In linguistics, asking what a person calls a woodlouse is a common question used to determine what part of the United States a person is from based on the name the person uses for woodlice. For example, in the south, they are almost always called "roley-poleys." In the northeast, they tend to be called "pillbugs." Other names may be used in other regions.

Woodlice in culture and cinema

Tuck and Roll were the woodlouse acrobats who appeared as supporting characters in the Pixar film A Bug's Life. They have been immortalized in a "Tuck and Roll's Drive'Em Buggies" ride at Disney's California Adventure.

See also

• Woodlouse hunter spider
• Giant isopod, the woodlouse's giant aquatic cousin