Underwater Flies or Xwixwiya:ye is a small, venomous crabs which are mentioned by natives of BC's interior. They are size of a man's hand. According to a Chilliwak resident, they behave and look somewhat like flies (hence being called "underwater flies") but have big claws and crawl around on the bottom. If they bite (I'm assuming "bite" refers to the pinchers) you, according to the natives you will die very quickly. Definitely some sort of freshwater crab, but of what kind I have no clue.