Fly Patterns - Spring Pupa

I know, it’s not springtime.  But that doesn’t mean that this little fly won’t work for you. If you turn over rocks in most any freestone stream, you’ll find little “green rock worms.” These bugs are caddis larvae. Without getting into the entomological intricacies of caddis species, some caddis larvae make cases and some are free-living. If you look closely at what you find on rocks or amongst the debris on the stream bottom, you’ll notice that the bright green “worms” can be of both types. In other words, there will be some crawling about, and others inside their cases. If you grab one of the little square cases and open it up, you will see what I mean. The little cased variety engage in “behavioral drift” from time to time at certain times of the day. This just means that they leave their cases and drift downstream where they establish a new home and build a new case. I don’t know (and entomologists say they don’t know either) exactly why this happens, but it indeed does. And, luckily for fly anglers, the fish know about this phenomenon. The Spring Pupa is actually just a chartreuse Fox Poopah, tied in exactly the same way as the regular Poopah series flies. In my experience, this fly works well as an imitation of either a free-living caddis larva caught in the current, or a cased caddis larva engaging in behavioral drift. I use it as a “stinger” (a third fly) off the bottom fly in a two-fly nymph rig. It saved the day for me and my client recently just above Pollard Flat on the Upper Sac, where it accounted for a good number of very large rainbows.