How do you tell a Striped Hairstreak butterfly from a Regal Fritillary butterfly? By using Butterflies of Pennsylvania, the most comprehensive, user-friendly field guide to date of all of the species ever recorded within Pennsylvania’s 46,056 square miles. Over 900 brilliant color photographs illustrate both the upper and under side of male and female specimens of each species, including skippers. Information on distinguishing marks, traits, wingspan, habitat, larval host plants, and handy facts offer assistance for field identification. The images depict the species in their native environments, as well as finely detailed museum-quality mounted specimens. County-by-county maps show where each species has been recorded within the state, and graphs detail when they are present and most likely to be seen. Butterflies are arguably the most recognized, studied, and beloved of all insects. They are essential to healthy ecosystems, agricultural viability, and ultimately human and animal survival. Butterflies of Pennsylvania will serve as a handy reference for a broad readership including students and educators, backyard butterfly enthusiasts and gardeners, conservationists and naturalists, public and school libraries, entomologists, lepidopterists, and butterfly watchers in general.