A. vulgare has been introduced to many locations in North America, where it may reach population densities of up to 10,000 individuals per square meter. They can live up to about three years. It is less susceptible to cold during the night, and may enter a state of dormancy during the winter in order to survive temperatures which would otherwise be lethal.
Armadillidium vulgare may reach a length of 18 mm, and is capable of rolling into a ball when disturbed; this ability, along with its general appearance, gives it the name pill-bug.
It feeds chiefly on decaying plant matter, but also grazes lichens and algae from tree bark and walls. Commonly found under rotting logs in the forest as well as inside homes or under boards that are outside on the ground.