The Northern California Fly Fishing Board

I'm not certain if October caddis are OBLIGATE terrestrial emergers, but I've never seen or heard of them hatching in open water. They crawl or swim to shore or to the down current side of obstructions then scramble out of the water to hatch. They are rather slow and methodical "hatchers" and evolution probably did a good job weeding out any who tried to emerge mid stream. They certainly have shucks but fish don't get a chance to see them.

If you are watching caddis bolt out of the water, it's likely another species (big Hydropsyches can be around in the fall) or possibly spent ovipositers who were resting on the film then suddenly decided that wasn't a cool place to hang out.