Errant Bugs

Yesterday, there was a black caddis on the front door of my office
building. We are about 300 yards from any moving water, that being a
slow drainage creek. I often see mayflies of assorted stripes at my
house. The house is 3 miles from the river. Not a lot, but enough to
peak my interest.
Does anyone know how far these things travel in the course of their
lives? I know a strong wind can blow them around but its been fairly
calm the last couple of weeks.
Frank Reid