Pill Bugs, also known as Sow Bugs, are the only crustaceans that have adapted to living their entire lives – as long as two years for adults – on land. Pill Bugs produce one to three generations per year, with females birthing from 24 to 28 young per brood.
Primarily nocturnal in nature, Pill Bugs feed on decaying vegetable matter and prefer moist environments under objects on damp ground and in basements. Pill Bugs will grow up to 3/4 inch long and their thorax is made up of seven hard, overlapping plates with seven pairs of legs. Only Pill Bugs are capable of rolling up into a ball.
Pillbugs are correctly classified as terrestrial Isopods, belonging to the Class Crustacea, which includes familiar crustaceans such as lobsters, crabs, shrimp, and daphnia (water fleas). (Factoid Source: Dr. Jonathan Wright, Department of Biology, Northern State University)