Saltflies were small, flying insects attracted to sweat. Rook was swarmed by saltflies whilst hanging from a hook in the Slave Market in Undertown. The hook he was hanging on restricted the space of his jacket and pinned his arms to his sides, preventing him from being able to bat them away. He could only wiggle and screw up his face to try and stop them lapping up the sweat on his sweat drenched face, but the flies continued to torment him seemingly aware that he could do nothing about it.