Written by: Bill Edrington, Royal Gorge Anglers
For many anglers, the words caddisfly hatch conjure up visions of epic days, when all you need to carry is a few Elk-Hair Caddis dry flies. Those who anticipate these hatches all winter long spend an inordinate amount of time designing and tying adult caddisfly imitations that will fool trout even in blanket hatches. But, while my experience with spring hatches, particularly the Mother’s Day caddis (Brachycentrus), has taught me that casting adult caddis fly imitations can certainly be a lot of fun, trout are often gorged on pupae long before the hatch actually occurs. The reason is simple. Caddisfly pupae can drift in the water column–from the streambed up through the buffer zone–for hours and miles until they discover the perfect water temperature and river conditions in which to explode to the surface and become adults.
If we ignore this behavioral drift, then we are literally robbing ourselves of hours of spectacular fishing opportunities. Also, after they’ve turned into adults, caddisfly adults don’t linger on the surface like mayflies do. Instead, they will flutter up off the water surface almost immediately. That’s why trout make such splashy rises to the dry fly. The trout must make a quick decision, and they often leap out of the water to take the adult before it flies off.
When teaching classes in fishing the lifecycle of the caddisfly, I have often been asked when you stop fishing a pupa and add an adult to the mix. The answer is: when you hear a splash that sounds like someone just threw their dog in the river. Many fish seem to slash at bugs just an inch below the surface. Those fish are generally feeding on pupae that are struggling to become adults. As I will explain later in this article, I continue to fish a caddisfly pupa even when I tie on a dry fly. I just drag a non-bead-head pupa pattern behind the dry fly.
Caddisly pupa patterns can be presented deep along the streambed, mid water column, or right up in the surface film. Over time, great caddisfly pattern designers like Gary LaFontaine, Gary Borger, and Mike Lawson, have designed caddisfly pupae to imitate deep-drifting and shallow-drifting pupae, mimicking dozens of different species of this little bug. Traditional wet-fly patterns designed by notables such as James Leisenring and Sylvester Nemes are absolutely some of my favorites. The purpose of this article is not to elaborate upon the virtues of one pattern over the other, but we must have a clear understanding of when to use certain “styles” of caddisfly pupae over the other. If you want to keep life simple, just carry olive and tan versions of the LaFontaine Sparkle Pupa in sizes 14 through 18. Tie half of them with a bead head and other half without. You can then follow the insect’s drift from the bottom to the top by adding or subtracting a split shot or two. Understanding that very few fly fishers adhere to simplicity as a philosophy, there are hundreds of weighted and unweighted pupae to choose from. We all have our favorites.
When and Where
Not all pupae drift along without a care. Some crawl out on rocks, and others–like the Giant October Sedge (Dicosmoecus)–swim to shore and crawl out to become adults. You will need to have a rudimentary knowledge of the hatch you are fishing in order to present a pupa imitation properly. Most species drift and swim to the surface, often struggling to get there, so that journey is where we want to focus our efforts. You don’t have to fish five days a week to learn how to fish caddisfly pupae, even though that doesn’t sound like a half bad idea. Unfortunately, most of us have to hold down the fort every now and then, so this is for you.
Case builders like Brachycentrus and net builders such as Hydropsyche drift in the water column as pupae, not larvae. Many fly fishers fish larva patterns during these hatches, but generally their success is due to the fact that there are other caddisfly species in the water at the same time–such as the Rhyacophila larvae which crawl around rocks freely, making them a great target for fishing larva patterns, especially on spring mornings before the case builders begin to chew out of their cases and emerge as pupae in the drift. By mid morning, you should be able to pick up fish on deep running pupae. This is the time when you can really benefit from using a water thermometer. Many anglers carry one in their vest or pack, but many folks aren’t really aware of when or why to use them. I’ve found that springtime is the best time to get your money’s worth out of a thermometer. On an April day, blue-winged olives will begin to hatch on cloudy days at around 40 degrees. On that same day, caddisfly pupae begin to drift in 50-degree water, give or take a degree, with an emergence at around 55 degrees. By using a thermometer, you can make pattern and technique changes that will keep you ahead of the curve. These caddisfly emergences generally take place in riffle water that is highly oxygenated, so don’t get caught fishing BWOs in flat water when the temperature is right for fishing caddisfly pupae. Caddisfly numbers usually exceed mayfly numbers, so most fish will move to the riffles to gorge themselves. Also, I’ve found that mayflies prefer cloudy weather and caddisflies prefer the sunny, slightly breezy days, so generally you won’t be faced with the dilemma of which to fish.
There are several ways to present pupa patterns, and most of them are very simple. For those of you who like to achieve a dead drift with a strike indicator, simply tie on a deep-running bead-head pupa and let it bounce along the bottom. Make your cast directly upstream and strip line back to keep up with the current or make a reach cast up and across with several mends to achieve a long drift. This method generally works best with the pupa near the bottom, but don’t prematurely pick up the line for another cast. Many fish will grab the pupa on the downstream swing as it pushes toward the surface in the current. This often results in vicious strikes, so be prepared. I encourage folks to keep their rod tip slightly upstream of the fly as it swings downstream. When you feel the weight of the fish or the heavy “tap” on the fly, set the hook by using a low-profile upstream sweep set. If you set the hook by lifting upwards, you will often remove the fly from the fish’s mouth, leaving you with your mouth open, spouting expletives. Don’t forget that a downstream take has everything working against you–the current, the weight of the fish, and human nature to lift the rod tip–so be patient and let the fish eat the fly before reacting.
Since many fish feeding on pupae will snatch them just below the surface as they emerge, the downstream techniques make a lot of sense. This is just a traditional “wet fly” swing presentation. I like to stand mid riffle, facing the cut bank shoreline, and make my presentation cast up and across with a reach cast or curve cast. As soon as the line is on the water and the leader is running properly, a mend or two will place the pupa in a nice dead drift as it passes in front of you. This should place the fly at its deepest position in the water column. All these steps are necessary to place the fly in the “strike zone” as it starts its downstream journey. As the fly line passes your downstream shoulder, make one more upstream mend and then let the current take the fly. This will allow the current to swing the fly from slightly below the surface up to the film, imitating the natural insect. That movement is what triggers the strike. You can also place a few small “lifts” or “wiggles” in the drift that will make your presentation more lifelike. Gary LaFontaine explained his presentation as a “stutter” achieved by holding slack line in the rod hand and releasing it in short sections.
As I stated earlier, I like to rig my pupa behind a dry fly. I use a larger attractor dry, like a size 14 Stimulator, when running a bead-head pupa on the dead drift. I use tippet sections up to 36 inches long with a #8 split shot above the pupa to place it deeper in the column. As fish begin to slash in the film, I switch to a foam-body Elk-Hair Caddis trailing an unweighted pupa with about two feet of fluorocarbon tippet separating the two flies. This method allows me to attract fish that want the pupa as well as fish that want a bug with wings. My favorite pupa for this rig is a LaFontaine Sparkle Pupa dropped off a Better Foam Caddis by Larry Kingrey. At times, just to change things up a bit, I put on a single soft-hackle wet, such as a size 12 Brown Hackle Peacock, and swing away. When fish are on a mission to eat every caddisfly pupa in sight, you can literally throw everything in the box at them and be successful to some extent. Just remember the behavior of the species you’re fishing and stick to those techniques.
A sociology/criminology professor for 25 years, Bill Edrington owned and operated Royal Gorge Anglers in Canon City, Colorado from 1990 until 2010, when his son Taylor took over. He is the author of Fly Fishing the Arkansas: An Angler’s Guide and Journal.