Larvae (singular: larva, meaning mask or ghost) are evil spirits that first appear in ancient Roman mythology along with some non-roman Italian lore. They represented vengeful spirits that didn't have an appropriate burial in life. These spirits of the dead had and will possess mentally weak humans, usually taking their spirit.
Lemures were formless and liminal, associated with darkness and its dread. In Republican and Imperial Rome, May 9, 11 and 13 were dedicated to their placation in the household practices of Lemuria. The head of household would rise at midnight and cast black beans behind him with averted gaze; the Lemures were presumed to feast on them.
Larvae and Lemures are believed to have the same common etymological origin as both are described as wandering and vengeful spirits that terrorize the living. Carl Linnaeus described the Lemures as being similar to the larva stage of insects.