During the Doctor and Riddell’s tour of the Nine Circles of Hell, they fought against many of the “savage insect races” that once ravaged our universe but are now condemned to eternal damnation beyond. Among the most vicious of these was the Hellgrammites. A parasitic species with a unique life cycle, the Hellgrammites absorb the bodies of the dead. In the cocoons that they weave around corpses, even the dead of other species will undergo a grim metamorphosis, only to rise and live again as newborn Hellgrammites. Possessing dozens of limbs and an instinctual bloodlust, the Hellgrammites are quick and violent predators. During the Dark Times, they were a plague upon our universe. Because of this, the ancient Time Lords banished them to the accursed dimension that evokes their name.