Btee Beetle

A Btee Beetle is a deadly parasite on Eolilgeten that burrows through the ears, into the skull, and leeches of the victims brains. When discovered early, they can be extracted from the ear. However, once it is inside the head, it can only be removed with magic: either a Beast Muse coaxing the creature out or Healing Muse who can perform surgery and repair damage. 
Btee Beetles are serious issues among the Inerts that live outside the society of Eolilgeten cities - they often have to abandon those afflicted in the woods or help them take their own lives.