A careful study of Miss Harriet Richardson's Monograph on the Isopods of North America (Bulletin 54, United States National Museum) shows only eleven species of what are commonly called sowbugs and pillbugs that might reasonably be expected to live in this region, judging from the latitude and climate in which they have previously been found.
Proceedings of the Iowa Academy of Science
©1923 Iowa Academy of Science, Inc.
"The Terrestrial Isopods of Iowa,"
Proceedings of the Iowa Academy of Science, 30(1), 197-199.
Available at: https://scholarworks.uni.edu/pias/vol30/iss1/42