Jason,
Just found your site....
In my neck o' the woods (Klamath Falls, Or.) the Fall Caddis, Limnephilidae dicosmoecus, is referred to as either the October Caddis or Orange Caddis. I recall that Schollmeyer lists it's size as 20-30mm. My "home stream" is the Williamson River and my adult specimans range between 20-22mm. Further, the hatch begins in earnest around the last week in September through October. I've also been able to determine that stream temperature, rather than time of day, is what triggers the emergance. On the stretch that I generally fish, this is when the temp rises to 40º, the emergance peaks at 42º, and stops altogether above 43º. On the Williamson, at least, this is generally about an hour and a half after the official sunrise and 2 hours before sunset, depending on the amount of cloud cover.
They do head for "shore" into tall grass and I've had specimans live for as long as 14 days.
I don't feel that my data for the Deschutes, Umpqua, and Rogue to be complete. However, I suspect that when water temps are within a few degrees of their averages, the emergance begins/ends.
I should probably stress that actual colors will vary from not only stream to stream but by "sections" as well. Generally, the body is greyish/orange and the wing a medium to dark ginger. I've found that as a "searching" pattern, during this emergance that a Large Ginger Fluttering Caddis (Orvis) on a 10-12 to be effective, an Elk Hair Caddis with Adams Grey/Orange body and dark Elk Hair (10-12) for the wing will do in a pinch. Personally, I use a design of my own making based upon the specimans I've captured. The important thing, IMHO, is that the wing be twice the length of the body and tied tentwing or downwing style.
I've experimented considerbly with patterns having translucent dubbing to imitate the shuck, my experience is that the "standard" dry patterns work best; fished wet or dry, with some movement. My observations are that because these flies emerge so quickly, particularly in deeper runs where there are outcropings or snags, that your "big ones" station themselves in a feeding lane and slurp...No splashy rises here. Tied with a small burnt orange/pale yellow egg sac at the tail and the wings slightly splayed and down is deadly....
That this is a significant hatch, would be an understatement and I agree entirely with LaFontaine's assesment. Hope this helps and I apologize for the length...
Dano
Edit in: BTW, I'm a transplanted Michigander and was astounded to find that the Williamson has, in fact, a Hex hatch that rivals those I fished on the Au Sable....