This is a well-illustrated treatment of and guide to all the fossil and present-day species of butterflies in one of the richest areas in North America for butterfly diversity and study. For much of the year, the meadows, forests, and grassy slopes of the Florissant region of central Colorado are alive with butterflies - nearly 100 species of these fascinating and beautiful creatures. Many of them have unusual life histories: the larvae (caterpillars) of one species take two years to mature; others develop close associations with ants; and the adults of some species live only a few days, whereas others survive for months in winter hibernation. Central Colorado is also the site of the florissant Fossil Beds National Monument, which has yielded 12 of the 44 known species of butterfly fossils in the world. To find fossils of these delicate-winged creatures in such a perfect state of preservation is one of the wonders of nature, since the fossils have endured 35 million years of geologic activity, erosion, and climate change. Remarkably, most of the fossil species are closely related to various present-day species.