Art Flicks' New Streamside Guide from the late 60's was all mayflies, but Dick Pobsts' Trout Stream Insects from the 80's had plenty of caddisflies; so if you knew someone that knew about caddisflies in the 60's & 70's it was ahead of the other 90% of flyfishers. Would probably be better referenced looking at the old FlyFisherman magazines to see when the caddisfly became a standard in many more flyboxes.