Explanation of Names
Woodlice comes from their superficial resemblance to lice, and their preference for cool, moist habitats like woods. The singular of woodlice is woodlouse.
Identification
In Armadillidiidae the tails (uropods) are shorter than the last abdominal segment.
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Most other families can not roll into a ball and have tails longer than the last abdominal segment.
In the following image Porcellio scaber is in the family Porcellionidae and Armadillidium nasatum is in the family Armadillidiidae. Note the length of the tails in each.
Range
Woodlice hide during the day anywhere cool and dark, so they're easily when the items they hide in are moved. They can be found anywhere humans live and cool, moist conditions exist.
Habitat
Woodlice need organic matter, which can be found in most soils, and they need cool moist conditions. Many places that might seem too hot and dry have cool hiding places where they can wait out the dryness and heat.
Food
Plant material, usually dead. If live plants are moist enough on the outside and soft enough, they will eat them and sometimes do damage.