Armadillidium vulgare may reach a length of 18 millimetres (11⁄16 in), and is capable of rolling into a ball when disturbed; this ability, along with its general appearance, gives it the name pill-bug and also creates the potential for confusion with pill millipedes such as Glomeris marginata.

[4] Armadillidium vulgare is able to withstand drier conditions than many other woodlouse species, and is restricted to calcareous soils or coastal areas.

[3] It feeds chiefly on decaying plant matter, but also grazes lichens and algae from tree bark and walls.

[6] A. vulgare is less susceptible to cold during the night, and may enter a state of dormancy during the winter in order to survive temperatures that would otherwise be lethal.

[10] Keeping a pet pill bug requires a very moist habitat with limited light and abundant decaying botanical matter.