No one knows what the Yahwie is. It appeared one day and slaughtered the Ananasi population, without warning and without hints at its motives. There are few things that frighten the Ananasi, but the Yahwie has become one of them. Even its name is drawn from aboriginal legends, describing a death-spirit from the beginning of the world. There are Ananasi that claim to have faced and defeated the Yahwie, but it always returns and it always succeeds. Even fleeing Australia proves to be no protection, as the werespiders later vanish and appear again on Australian soil, dead.
Some Ananasi, however, suspect that the Yahwie seeks vengeance against the were-spiders for their part in the fall of the Bunyip. Evidence for this is that the corpses are usually found at desolate Bunyip Caerns. Also, the Yahwie never targets anything else but the werespiders.