Another Black Stone Fly. The Little Winter Stone Fly would be about the length of the head of this big boy. If you see a hatch of the big ones or the little ones.....get an imitation on immediately. Fish subsurface or as a dropper with dry. The don't emerge and fly away off the surface like a Mayfly. They will crawl to a rock, or stationary object in the river and shed it's shuck then fly away.