These land-dwelling crustaceans are arthropods but not insects. They are worldwide in distribution. In the United States the 2 most common species are Porcellio laevis Koch and P. scaber (Latreille) both in the family Porcellionidae and of worldwide distribution.
Adults up to about 5/8″ (16mm) long convex above but flat or hollow beneath. Color dark to slate gray. Typical of crustaceans sowbugs with 7 pairs of similar legs 2 pairs of antennae 1 tiny the other readily visible: body dorsoventrally flattened (top to bottom).
Because of water loss is such a problem. Sowbugs are inactive during the day and remain hidden under objects to reduce moisture loss. During the day they can be found around buildings in such places as under trash boards rocks flower pots piles of grass clippings flower-bed mulches and other decaying vegetation.