What is an October Caddis? Know Your Flyfishing Bug

Fall fly fishing is often characterized as a time for precise casts, small mayfly patterns, and great drifts. And then the October Caddis comes along. The October caddis is a lumbering, awkward, skittering mess on the water and a big bite for trout that seldom goes unnoticed. But what exactly is an October Caddis, and how should you fish them? Lets sort it out.

Big, bulky and bad at floating. What else is to love for a trout? October Caddis photo via Flycraftangling.com

What is an October Caddis?
The October Caddis is a surprisingly large, clumsy caddis that hatch on rivers in September and October. Fly Anglers refer to these bugs most often as “October Caddis”, or “Fall Caddis”, though this has little to do with their scientific name, Dicosmoecus. Technically, there are four known Western species under this family name, but their minute differences are of little importance to our angling. Bugs of the Dicosmoecus family undergo a complete lifecycle. Eggs hatch into larvae, the larvae build cases on the river bottom, then mature through a series of installs (stages of maturation) before sealing off their case and pupating. During pupation, the relatively featureless larva grow wing buds, gills and become strong swimmers. The pupa then cuts itself from its case and swims to the surface and to the shoreline to climd rocks and shed it’s pupal membrane to emerge as an adult. The adult October Caddis then flies to nearby bushes and trees, where it will live for several days mating and with others. The females then return to the water to oviposit, or drop their eggs. Unlike mayflies, that only perform this ovipositing once before dying, caddis can live for a few days performing this mating ritual again and again. In a typical fall day in a stream where October Caddis are present, fish will be interested in just the last stages of this process, keying in on and eating the pupa as it swims to the surface and emerges, and the adults that return to the water to deposit their future offspring.

Why Are October Caddis Important for Fly Fishing?
What makes the October Caddis an important hatch for anglers is their size and behavior. Typical pupas range in size from 20-25mm, or 3/4 to 1 inch long. The pupas are also bulky, and present a large bite of protein in a time when most other hatches are much smaller mayflies such as Blue Wing Olives and Mahoganies. The adults also offer up a large chunk of protein, but come with the added bonus of awkwardness on the water. An adult October Caddis flitters about on the water, and often return to the water over and over again, giving fish plenty of opportunity to take them. For anglers fishing tiny flies with long leaders, the opportunity to skate and skitter a large dry fly over the heads of fish can be a welcome change in the fall, and can elicit voracious strikes from larger fish.

How Can I Tell that Fish are Eating October Caddis?
Seeing fish eating October Caddis is not a regular event. Because they hatch in smaller numbers than other available food in the fall, fish rarely are eating October Caddis exclusively. Rather, it is much more important to be looking for the presence and signs of the October Caddis being in the drift and part of the available food for trout. Adults emerge in the early afternoon until dark, but because they can live for sometimes close to a week, it is worth shaking some bushes early in the morning to see if any adults are present. Likewise, looking for the telltale bright orange shucks on rocks along the shoreline is a great way to find out if the October Caddis is about in the river you’re fishing. Flipping rocks in slow, inside bends will reveal the large larval cases, and more empty ones than full ones will also let you know it is a great time to tie on an imitation.

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What Flies Do I Need For The October Caddis Hatch?
Lucky for anglers, many flies will cover this big bug and often they are bugs we are already carrying in our box. It isn’t entirely necessary to carry an exact replica to catch fish. An orange chubby chernobyl in sizes 10-12, a larger orange stimulator in the same sizes, or a big bright goddard or elk hair caddis will do nicely as an imitation of the adults. The pupal stage can be covered by flies like an orange rubberlegs, a larger copper john, or a more precise caddis pupa imitation. More important than the fly used in both situations is how it is fished, and the water in which it is tried. In both cases of the pupa and the adult, or the nymph and the dry fly, this is far more important and takes some almost opposite thinking than most of our fall fishing.

How Do I Fish The October Caddis Hatch?
Lets start with the nymph, or pupa. The pupa of the Dicosmoecus family are strong swimmers, though they prefer to swim through the slower water to find rocks to emerge on. For this reason alone, the old standard swing through a run and into the slow inside bends, then a slow hand to hand retrieve back to the angler can sometimes entice the fish into striking. This is a great imitation of the nymph’s behavior. A nymph run through the deep holes after a riffle, then swung out into the shallows  is often considered a less active form of fishing, and an older technique more accustomed to wet flies and soft hackles, but it is ideal for the october caddis emergence.
As for the adults, their awkward flying is in direct contrast to the pupa’s excellent swimming. For this reason, beginners often have better luck with a single October Caddis dry fly than a technical mayfly rig. The dry fly can be skated, skittered, twitched, dunked, splatted, and generally moved all around the water to elicit strikes as this ugly drift actually more accurately imitates the adult October Caddis when it is ovipositing. Like the nymph, the water the dry fly is run through is also almost counterintuitive. When fishing a small mayfly or other fall pattern over slow, deep holes where larger fish are hugging the bottom often the fly will be completely ignored. But the large meal and easy target that a clumsy October Caddis presents will sometimes draw a large cutthroat up from its otherwise cozy home at the bottom of the stream. When fishing the dry, give attention to the riffles and runs, but never ignore the slow water that might hold a whopper.

Leader Setup
Long leaders in the fall always give you a big advantage, and in the case of the October Caddis, a 9 ft. leader with a short section of fluorocarbon tippet will often suffice for turning the fly over, and adding the distance and invisibility that is necessary for the fall. A 9 ft. 4x leader with 4x tippet is just fine for this situation. When fishing the nymph, a 4x leader will also suffice. Fished tandem with a slim mayfly nymph, the october caddis pupa is a great attractor even if it doesn’t take as many fish as the mayfly swung along with it.

Last Words
Fall is a great time to be on the river, but often can be a very frustrating time as well for the amateur angler. Small flies, technical drifts and clear water make fish quite wary. The prospect of fishing a larger fly that doesn’t require this kind of technical prowess make the October Caddis hatch an event worth looking forward to, and often even if the adult isn’t present I will fish these imitations in the afternoons. Give it a shot next time you’re at the river, and focus your efforts on the water you might have missed with the mayfly. You could be rewarded with a beautiful fall cutthroat to match your big orange fly!

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