The emerging pupae run about a size 16 and have green bodies and black wingpads. They don’t waste time getting to the surface so when matching the rising pupae, don’t be afraid to swing them at the end of your drift. This mimics a vulnerable caddis racing to the surface, trying to elude predators before hitting the surface film. This scenario is made for swinging soft-hackles, so don’t be afraid to whip out the trout spey gear.
Once these caddis hit he surface you can match them with emerger patterns that float half-in/half-out of the water. LaFontaine’s Emergent Sparkle Pupae is one of the most popular patterns out there, but many work. You can also fish your standard dries at this time, such as Goddard’s and Elk-Hairs. I’ve never seen the true dry outfish an emerger during this hatch, however, and I’ve been frustrated at times when I’ve tried to make it happen with a true dry and been snubbed by the fish. So think rising pupae and emergers during the afternoon hours and you’ll be good to go.
By late afternoon you may see the female caddis returning to the river to deposit eggs. Some land on the water and swim to bottom to attach their eggs to substrate; others just land and let go. In either case there is mega-mortality so fishing a spent-wing style crippled caddis, with a dead-drift and a slight twitch from time to time, is a good move. Fish it until dark if the bugs are still landing. You can pick up some good fish at this time, meaning the big, lazy boys that don’t work too hard for their meals.
As mentioned, this can be a difficult hatch to hit right, but you won’t forget it when the conditions and bugs align. I got that scenario one day on the Yellowstone, below Livingston, when nobody else was on the water. I couldn’t find fish in the big, main flow, but a couple side-channels were loaded with big browns that knew the bugs were coming. When the emergence happened I took a couple 20-inchers on emergers and many other fish in the 14-to 18-inch range. I’ve pulled off similar stunts on the upper Clark Fork near Deer Lodge, but I’ve also been handed my ass on the lower Madison—probably fished a dry fly when I probably shouldn’t have, meaning I threw an Elk-Hair Caddis when I should have thrown a pupae or an emerger.
Let’s say you know the caddis are coming off and you get to the river only to find it blown. Is it a worthless escapade? No way—if you get to see this caddis event—literally billions of bugs flying in the air at the same time, with red-wing blackbirds and swallows diving on them, you won’t forget it. It’s one of the West’s amazing natural phenomenons. Trout on the end of al one are the bonus. —Greg Thomas