Etymology: The species name placidus is derived from a Latin word for smooth or pleasing, probably based on the smooth surface on its head.
Comment: Adult beetles attracted to lights. It is one of four species of Genus Lucanus occurring in the United States, rather uncommonly collected compared to other three species.
No known detailed records of biology for L. placidus is known including online pages, however, their life cycle is about an year in my experience, and they are not at all difficult species to rear or breed. Easy to have major males/females emerged in less care compared to many different other species among the species of Genus Lucanus.