|First appearance||Once More the Nightmare Factory|
Underwater flies are small, venomous crabs which are mentioned by natives of BC's interior. They make their first and only appearance in Once More the Nightmare Factory.
They are called Xwixwiya: ye, and are the size of a man's nail. 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, will die very quickly. Probably some sort of freshwater crab.
Underwater flies eat algae.