The spring grannom caddis hatch on the McKenzie is an odd one. When the hatch is light, it can make for some good dry fly fishing. On sunny days when the bugs come off in profusion, however, they make for some very difficult fishing conditions. Why you ask? Because there are literally billions of them on the water at a time. Yesterday between noon and two o’clock, there were mats of these bugs on the water, with multitudes more hovering over the surface, appearing from a distance like fog. Basically, it is a drought of abundance, there is so much food available to the fish that there is no compelling reason for them to pick your fly out of the horde.
Often during this hatch, I do better fishing attractors like a small Royal Wulff or Royal Trude than I do using an imitation of the caddis itself.
Weather always influences the relative abundance of different hatches. The cloudy days this week have brought good mid-day March Brown hatches and very good trout fishing. The sunny days, however, have provoked fish and angler-choking swarms of the small caddises. Fortunately, this caddis hatch is usually fairly short-lived, and hopefully the brunt of it is over. I anticipate that we have got maybe another week to ten days of the March Brown hatch to look forward to, after which smaller and paler mayflies will take center stage.
Yesterday was 65 degrees and sunny and the caddis came off by the billions. I was guiding a couple of guys from the Salem area. After an unimpressive start, I decided that we would be best served by nymphing through the caddis swarm, an approach which yielded a good number of big wild rainbows.
Ethan Nickel Outfitters 
So people drive all the way to Montana for the Mother’s Day Caddis hatch, but it’s been going on here in Oregon this whole time? Hilarious! I spent a week on the Yellowstone and tribs a few years back, lured there by the hatch. That trip convinced me that Montana is highly overrated. The McKenzie, however, seems to be underrated.