White-nose syndrome (WNS) is a devastating disease affecting hibernating bats, first documented in winter 2006 in eastern North America. Over 5.5 million bats of several species may have died as a result of this disease. The fungus Geomyces destructans is now considered the causal agent of WNS, and this species may have been recently introduced into North American bat hibernation habitats. This overview summarizes the ecology and distribution of Geomyces fungi. Species in this genus are common in the soils of temperate and high-latitude ecosystems and are capable of withstanding and thriving in cold, low-nutrient polar environments. These species are dispersed by wind, groundwater, arthropods, birds, and mammals and are carried by humans, their clothing, and their equipment. These characteristics present significant challenges to biologists, managers, and others charged with controlling the spread of WNS and G. destructans in other parts of North America and the biosphere.