Trouts Journal

Understanding The Caddis Life Cycle

Ivan Orsic / Apr 19, 2022

Due to their complex life cycle, sporadic behavior, and unusual looks, caddis tend to be underappreciated by many fly anglers. However, the caddis fly is one of the most important flies to have in your box no matter where you choose to wet your line. Below is an overview of the caddis life cycle, a go-to fly to imitate throughout the spring and into summer and most known for the famed “Mothers Day” hatch here in Colorado.

An Overview of The Caddis

If an angler were to take a representative sample of all the waterways in North America, the angler would find that the number of caddis species far outweighs the number of mayflies and stoneflies. Caddisflies are more resistant to strenuous water events (temperature changes, rising and lowering of water flows, etc.), and caddis can survive in a wider variety of climates and water systems–existing in the DSP and Alpine Lakes–when compared to bugs such as the stonefly. The widespread nature of the caddis makes them a desirable option for trout in just about any river system.

Whether it is the lack of comprehension, unusual looks, or the combination of both and the complexity of the caddis life cycle, the caddis is often unused to its full capacity.

Another point worth noting is the caddis's erratic behavior while in the water–darting in and out of the water and fluttering around unpredictably. Too much drag, high speed, or movements that counter the current are perfect examples of what not to do with nymph patterns and are typically frowned upon with other insects, but this is perfectly okay for the caddis larva and pupa, to a certain extent.

Made up of four primary stages (Egg, Larva, Pupa, Winged Adult), the Caddis goes through what is referred to as a Complete Metamorphosis. It resembles the life cycle of a moth or butterfly rather than a mayfly or stonefly. Given the Latin name Trichoptera meaning “Hair Wings,” the adult Caddis will have four wings, each fluttering in a 180-degree motion providing the loft and stabilization the fly needs to flutter above or dip on the water when it is time to lay eggs.

With a life cycle lasting roughly a year, the life stages trout are primarily concerned with is the Larva, Pupa, and Adult. However, for the angler to understand and become more knowledgeable about the insect, the angler must understand the life cycle. The words below do just that.

The Caddis Life Cycle

The caddis life cycle is segmented into four distinct stages and is considered a Complete Metamorphosis. This means that each stage from egg to adult will look entirely different from one another throughout the Caddis's life, ultimately bearing no resemblance to its infant stages. Bugs like beetles, butterflies, and moths are great examples of other insects that undergo complete metamorphosis as well.

The Early Stages:

Much like the Mayfly and Stonefly, the Caddis Life cycle begins with the female Caddis depositing eggs on or below the water's surface. A process that may take several days to complete. Once the eggs have been deposited, they typically fall to the bottom of the lake or river bed, where they will incubate for about two weeks before hatching. The trout doesn't pay attention to the egg stage, so neither should the angler.

The Middle Stages:

Once freed from the egg, the caddis is now in the larva stage. During the larva stage, the main goal is to eat. The larva feeds on any biomaterial available, which typically come in the form of plants, but sometimes a dead fish can serve as an option as well. It's safe to say that there are many species of caddis and each one has a different way of going about their world. As mentioned previously, the caddisfly is very resilient and can exist in various water types. This is due to their adaptation to living in various ways during the larval stage.

Free Livers:

This larva does not build a case but utilizes its camouflage to roam freely on the bottoms of rivers or lakes. These types of larva are pretty crafty and typically stay out of the snub-nosed reaches of trout.

Net Spinners:

While these larvae do not build a case, they reside in the openings in rocks, branches, or downed logs and spin a web to collect their food.

Tube Makers:

These are the larva who burrow and construct tube-like formations in the bottoms of rivers and streams. Be mindful that, while impressive, they do not possess the drudging rock power of a modern machine, so this larva will typically be found within lakes, streams, and rivers with mud, sand, or clay bottoms.

Trouts Pro Tip

"If you want to know the entire list of how Caddis make their homes. Check out "A Guide to Aquatic Trout Foods""
- Only A Few Copies Remain!

Once the larva has gotten to an adequate size through eating, it will transition to the most crucial life stage, the Pupa. The caddis “hibernates,” mimicking a butterfly or moth, drastically changing its appearance during this stage. While in the security of a pupal casing it has formed, the caddis pupa will develop wings, appendages, air-breathing gills, and reproductive organs–a complete metamorphosis. During this part of the stage, the pupa is not often available for the trout; the pupa typically hides in the cracks and crevices of rocks or in their case.

When this pupa emerges from their casing, they are often a lovely meal for the foraging trout (read: plump and nutrient-dense), especially on their journey towards the water's surface. While other types of emerging insects are clumsy and stumbling swimmers at best, the caddis pupa is not. The caddis pupa is strong and graceful in the water, often moving towards the water's surface with haste. A bug on a mission.

The Adult Life:

Once at the water's surface, the caddis pupa launches itself out of its skin, transformed into a full-fledged air-breathing adult caddis. Typically, the caddis wastes no time making this transformation and quickly sprouts its wings and begins fluttering on the water to dry its wings. Unless an angler is in the presence of an event such as the Mothers Day Caddis Hatch, noticing individual caddis hatch is often tricky until multiple are fluttering out in the air. Like the mayflies and stoneflies, the caddis immediately seeks refuge among the trees or river banks. Once they are in the safety of foliage, like species will congregate together and begin their mating process, which can take several days.

Moth-like in shape, the adult caddis is an erratic but strong flyer. The adult caddis typically waits until the afternoon or evening hours during the spring and summer months for mating practices or egg-laying. At this time, an angler can observe the caddis fly dipping on the water–typically the female–depositing eggs on the bottoms of lakes, rivers, or streams, thus starting the life cycle of the caddis once again.

Final Thoughts

The caddis life cycle is essential to anglers. However, only the larva, emerging pupa, and egg-laying adult are the ones an angler should focus their attention too. For those looking to pick out caddisflies for their next trip, opt for ones that represent the three life stages mentioned above.

I hope you enjoyed this overview of the caddis life cycle. Stay tuned to the blog, where we will be going over other important insects. If you have questions regarding hatches, we have a dense selection of books perfect for any skill level. If you want to expand your knowledge on bugs, check out our Bugs for Beginners class hosted at our Denver shop location!

No matter your skill level here at Trouts, we want to ensure that your time on the water is well spent. That means we want to answer any questions you may have regarding hatches, flows, or where to fish this weekend.



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