A guide to 65 species of butterflies common to the American Midwest. Using digital photographs instead of drawings, the guide shows sexual differences between males and females, seasonal forms, and both the upper- and undersides of wings when these are critical for proper identification. ''Our customers love Prairie in Your Pocket. It's perfect not only for your pocket but for your backpack or on your car dash. We can't wait for more.'' ''Prairie in Your Pocket moves faster than a goldang prairie fire. I can't wait to see Iowa's next addition to their nature guide series.'' Steve Hendrix is professor in the Department of Biological Sciences at the University of Iowa. Diane Debinski is associate professor in the Department of Ecology and Evolutionary Biology at Iowa State University.