How to Identify a Caddis and Hatch
Caddis Character Traits
Starting off, let’s discuss the physical characteristics when defining how to identify a caddis. Caddisflies, belonging to the order Trichoptera, are often mistaken for moths due to their tent-like wings when at rest. Their two pairs of wings are usually hairy, which differentiates them from mayflies and stoneflies. Honestly identifying a caddis is really easy. Adults have long, threadlike antennae that can be up to twice the length of their body. Their body colors range widely from pale creams and olives to deep browns and blacks, providing clues to their specific species and habitat.
Fun Fact: Adult caddisflies have a unique, tent-like wing shape which makes them recognizable. During their short adult lifespan, they're prolific fliers, often seen skittering across the water's surface, especially in the evenings. This erratic movement is imitated by fly fishers with dry fly patterns known as "caddis skaters" or "skating caddis." They are true masters of flight, like well-trained fighter pilots.
These are Mother's Day Caddis. Notice the orange color, size and great looking cases!
The larval stage is significant for fly fishers because trout feed heavily on caddis larvae. These larvae construct protective cases made from twigs, sand, small stones, or other debris. The cases can be tubular or spiral, with the design depending on the specific species. This behavior can be mimicked by fly fishers using patterns like the Peeping Caddis or a Jigged Peek-A-Boo Caddis. Observing the type of case a larva builds can also help in distinguishing between species. There are a few go-to patterns that are absolutely deadly in most circumstances. I can only assume they taste like candy because fish always seem to have an appetite for them. Know that we identified caddis in adult and larvae phases let's look at a few flies.
Fun Fact: Caddis fly larvae are known for their unique ability to build protective cases using materials they find in their environment. The architectural larvae use silk to bind together sand, gravel, twigs, or even small bits of aquatic plants. Different species of caddisflies construct distinctively different cases, and some don't build cases at all. For the fly angler, imitating these larvae (and their cases) can be very effective when fish are feeding on them. On the other hand, there are jewelers, dubbed artists, who have raised caddis to produce cases built with gold, diamonds, and other precious metals and stones. The patterns are remarkable and all unique.
Adult Patterns: Goddard Caddis, Elk Hair and CDC Caddis, X-Caddis, Missing Link Caddis
The Goddard Caddis is a great adult pattern for many situations
The Elk Hair Caddis and CDC is a high floating and is a staple pattern for me.
The X-Caddis is a great choice. It falls into an adult cripple pattern that is great for picky trout
The Missing Link is a go to for skittering patterns and is looked at as an adult or crippled adult.
Nymph Patterns for Larvae: Peeping Caddis, Jigged Peeping Caddis, Tactical Grub Caddis, Flashed Jig Caddis
My go to fly for caddis fishing. Heavy with high action make it extremely effective everywhere.
Another version with lesser action but drops through the water column fast!
Simple caddis larvae pattern that can be a great alternative to the others and works great as a dropper fly.
Another dropper fly for me. I fish this under a hopper very commonly.
Emergence and Hatch Patterns
Caddis hatch can be explosive and short-lived, making it an exciting time for anglers. Now that you know how to identify a caddis hatch, seeing details is key. Fore example, during a hatch, caddis typically emerge quickly and in masses, often causing a frenzy of feeding activity among trout. Unlike mayflies, which can float on the surface for a while during their emergence, caddisflies tend to skitter across the water surface, leaving a distinctive v-shaped wake. This behavior can be mimicked using flies with a bit of elk hair or deer hair, which provides the necessary buoyancy, allowing the angler to "skate" the fly on the water's surface. Patterns like the Elk Hair Caddis or Goddard Caddis are effective during these hatches.
Trout activity during a hatch can be confusing. Haffle, Hughes, and Morris describe this deeply in their book Tactics for Trout. Summarizing their input comes down to looking for the type of eating behavior that you are witnessing. There are two types you should see, the top eat, and the emerger eat. Telling the difference between the two is by watching the gulp or splash. A gulping eat where it is subtle, but leaves bubbles is a top eat. Conversely, when an emerging caddis is rising through the water column, fish tend to chase, and you will see a splash or a leap. These aggressive eats are more commonly than not mischaracterized as dry fly eats, and it can be ultra frustrating casting to rising fish that you think are eating adults and eat everything around you but your fly. Instead, fish wets or a dry dropper with a wet underneath, and you will be pleasantly surprised.
Fun Fact: Unlike many aquatic insects that migrate to the shoreline to pupate, most caddisflies undergo their pupal stage underwater. They construct a special pupal case or cocoon in which they metamorphose into adults. When they are ready to emerge, the adult will break free from its pupal case, swim to the surface, and fly away referred to as underwater pupation. This process is another feeding opportunity for trout and other fish, and hence, another target for fly patterns.
Nymph Patterns for Emergers and Pupae: Baltz CDC Caddis Pupae, Holy Grail, Capped Avenger, Soft Hackle Caddis
These are all deadly patterns. My approach to emergers and pupae is all about speed to depth. I do that with weight and the Avenger is thin and fast. The key here is the rise. Often you'll see takes when you lift your rod tip or a dropper is rising as it is being dragged along by a hopper or indicator.
Season, time of day, and water conditions play a role in predicting a caddis hatch. While there are numerous species of caddisflies, many tend to emerge in the late spring to early summer, often during the late afternoon or evening. Overcast or drizzly conditions can also prompt a hatch, making these seemingly less-ideal fishing days some of the best for targeting caddis-feeding trout. To further enhance chances of success, anglers should be observant for signs such as sporadic rises of trout or the presence of caddisflies in the air or clinging to streamside vegetation.
Fun Fact: Caddisflies are sensitive to water pollution, especially to changes in pH levels, temperature, and the presence of toxic substances. Their presence in a water body is often considered a good ecological indicator of the health of an aquatic ecosystem. As a result, ecologists frequently use caddisflies in biomonitoring studies to assess the health of freshwater habitats.
Take the next step and learn more about how to fish a Caddis in this article.
Understanding these technical aspects and nuances of caddisfly identification and behavior, fly fishers can more effectively select and present their fly patterns, increasing their chances of a successful day on the water.
Because caddisflies are found all over the world, with over 12,000 described species! They inhabit a variety of freshwater habitats, from fast-flowing mountain streams to still lakes. Their global distribution means they're a key food source for fish in many different ecosystems. For the fly fisher, this means caddis patterns are essential in the fly box no matter where you're fishing.
If you liked this article, you'll enjoy "How to Identify a BWO"
By Christian Bacasa
Host of the Fly Fishing Insider Podcast