Written by: Brian McGeehan, Montana Angler Fly Fishing
The Mother’s Day caddis is a legendary hatch, and one of my personal favorites of the entire year on the Yellowstone in southwestern Montana. There can be a literal blizzard of caddisflies in the air, appearing as huge oscillating waves over the water. The tough part, of course, is timing the hatch. The big blitz of bugs usually lasts for a at least a week or so, but sometimes cold weather causes it to sputter or stop and start again. Water clarity is the real issue, as this hatch is jammed right up against the start of runoff. Some years, everything works out perfectly, while other years the entire thing gets washed away. The good news is that we can also chase this hatch on the Madison River, which remains clear because of the dams along its course. We have so much good fishing around the Bozeman area that we do not have to put all our eggs in one basket.
Back to the Yellowstone: if you are planning a trip for the hatch, look to the first week of May as your pick, but spring weather is so unpredictable that the hatch can be earlier or later. In my experience, it seems that when the water temperatures start to creep above 50 degrees in the afternoon, that signals that the hatch is eminent. When things really get cranking, you can have productive dry-fly fishing all day long, although afternoons and evenings tend to be the most consistent times for fishing. The fish tend to be a bit less shy about feeding on the surface once the sun begins to get off the water.
For flies, I like an olive or tan color in a size 14. Sometimes I’ll drop to a size 16 if the water is exceptionally clear. A traditional Elk-Hair Caddis or X-Caddis works fine, but I prefer some version of a Parachute Caddis. The colored parachute post makes it a bit easier to see the fly from the boat.
The trout will often key in on emergers during the caddis hatch, especially during bright, sunny parts of the day. To make the most of this, I often drop a caddis emerger off the back of my dry, and it typically catches at least as many fish, if not more, than the dry. Patterns such as a Z-Wing Caddis Emerger or CDC Caddis Emerger are my top choices.
This is one of those hatches that every serious fly angler should try to experience at some point in their fishing career. While it does breed its fair share of frustration at times, timing it right will produce enough fish stories to forget about all the rest.
Brian McGeehan is owner and outfitter of Montana Angler Fly Fishing, an Orvis-Endorsed Fly-Fishing Expedition in Bozeman, Montana.