Lemures, a.k.a. Larvae, are the earth-bound, malevolant spirits of the dead in Roman mythology.
Appearance: Lemures normally appear as autonomous shadows, disconnected to any human being. Lemures in the form of Larvae, can transform into horrific forms, usually to frighten their victims.
Lore: Evil people, victims of horrible crimes, and people who did not receive a proper burial or time of mourning were believed to transform into Lemures, the evil spirits of the dead. Lemures can attack and drain the life-force of people, similar to astral vampires, Lemures can cause disease in both men and animals, ruin crops, and can cause poltergeist-like activity. Lemures were believed most active in the month of May.
Powers: Lemures can cause sickness and death and bring ruin to a household.
Defense Against Lemures: To pacify the Lemures and prevent their wrath, the Romans would perform a ritual in which the male head of a household would place black beans in his mouth. He would then spit these into his hands and throw them behind him. The Lemure were then believed to feast on the beans instead of the living. If this ritual failed, the family would beat on pots to produce such a noise to scare the Lemures away.
Trivia: The Madagascar animals called Lemurs are indeed named after the Roman Lemures. Also, young of certain insects called "larva" are indeed named after Larvae.
Ritual To Rid One's Home Of Lemures