Adults grow to about 3/8 inch long, have a number of rounded body segments and seven pairs of legs. Sowbugs possess a pair of tail-like structures on the back end of the body. Pillbugs do not have these structures and are capable of rolling into a tight ball when disturbed, a behavior that resulted in their common name, "roly-polies."

Arthropods in this order: pillbug, scud.