Over the past decade, 84 species of dragonflies and damselflies (Odonata) have been found in an area <0.6 km² (<0.25 mi²) within Idylwild Wildlife Management Area in Caroline County, MD. Eighteen of these species are species of conservation concern in both Maryland and nearby Delaware. This high level of Odonata diversity exceeds that of any other known location on the Delmarva Peninsula. We attribute this to the presence of a variety of pond, marsh, and bog habitats resulting from the unimpeded natural succession of an abandoned sand- and gravel-mining operation. This site has provided a refuge for locally rare species in a heavily agricultural region where draining of swamps and channelization of streams destroyed otherwise suitable wetland habitats for many now rare and endangered Odonata species. Deliberate planning resulted in the decision not to interfere with the ongoing natural succession in the Idylwild Wildlife Management Area, enabling colonization and persistence of Odonata species of conservation concern.