Hans, the Tan Caddis that you have seen from time to time in the Smokies has been refered to as the Giant Tan Caddis, the October Caddis, Cinammon Caddis, Orange Sedge, and probably some other names. It is very prevalent in almost all of the streams of the Smokies. The reason that you've not seen the large hatches of them is because they do not hatch very much until after dark. Try driving into some of the campgrounds that are right beside the streams after dark and see how large numbers of them are drawn to lantern lights. I can't really say if they are the same insect that is in the Northwest, but fish really like them and it is one of their major staples to get ready for the winter.
Hugh Hartsell---East Tn.
P.S. I hope those allergies are calming down.