Tachopteryx thoreyi occurs in localized populations throughout Alabama and most of Mississippi (likely absent from the Mississippi River Delta). This large, primitive, gray and black species is often found perching vertically on tree trunks in or near forested seepage areas. These seepage drains are the breeding and nymphal habitat, and the nymphs live among the wet leaves and muck of the seeps, rather than underwater. The Gray Petaltail is very unwary of, and often will perch on, humans.