What is a Caddis (or Sedge)

385- What-is-a-Caddis

Sedge or Caddis Flies

To freshwater fly anglers, especially those who frequently ply the trout and steelhead water of the western portion of North America, the caddis or “sedge” is a fish catching machine. Western fly anglers aren’t the only ones benefiting from the fish-catching power of caddis; they are available to trout in good numbers across the globe.

Caddis flies are relatively large aquatic insects that provide hungry trout with an excellent source of nutritional protein, making understanding their typical life cycle and the ability to identify them from larva to adult important aspects of freshwater fly fishing.

Caddis, unlike mayflies and stoneflies, undergo complete metamorphosis, experiencing larva, pupa, and adult stages within a typical life cycle, rather than just a single nymph stage.

During the larval stage, caddis look like tiny, segmented worms. These wormy creatures are classified as either cased caddis larvae or free-living caddis larvae.

Cased caddis spend the duration of the larval stage protected by a self-constructed case. Cases are cleverly and resourcefully fashioned of vegetation, gravel, and other tiny bits of debris and held together by a sticky silk secreted by the bug specifically for this purpose. Cased caddis are prolific in all types of trout water because of their aggressive nature and ability to feed on active, similarly-sized prey.

Free-living caddis larvae can be found cruising on the river bottom or hiding beneath the shelter of spun silk “tents.” Free-living caddis require strong in-flowing or out-flowing currents for survival as they make a living by trapping their food in bits as it flows by them.

Colors for the most common species of caddis larvae range from greyish-white to reddish-brown to a bright green color known in fly fishing and fly tying as simply “caddis green.”

As pupae, caddis are at rest. During this life stage, the insect constructs a shelter of rocks or silk and remains in this cocoon until it is ready to hatch into a winged adult. When the caddis pupa emerges from its cocoon, still encased by its translucent pupal shuck, it swims quickly to the surface film to complete its emergence.

Ideally, caddis emerge from their pupal shuck as quickly as possible as they are extremely vulnerable when hanging in the surface film. Once the winged adult caddis has fully emerged, it continues to act with a keen sense of urgency, wasting no time to flitter from the water’s surface and to the safety of nearby trees and stream-side vegetation.

Adult caddis live significantly longer winged lives than mayflies and will spend up to two or three full weeks away from the water. When they’re finally ready to mate, males will gather near their home water to form a swarm. Females will join the swarm to have their eggs fertilized. Once the mating process has been successfully completed, females will deposit their eggs on the water’s surface, propagating the species.

Caddis are imitated by fly fishers and fly tyers in five distinct points of the life cycle: larvae, pupae, emerger, cripple, and winged adult. Both larvae and pupae imitations are fished entirely beneath the water’s surface and both are designed to imitate these sub-surface life stages. An emerger is a specific artificial fly designed to imitate caddis during its emergence from pupa to winged adult and is fished just beneath the water’s surface or within the surface film. A cripple is similar to an emerger, but designed to closely imitate and emergent caddis that has been caught or trapped in the surface film by its own pupal shuck, unable to hatch into a winged adult. The remaining artificial is a dry fly designed and fished to imitate the caddis (usually a sexually mature female) during its adult life stage.

When packing your fly box with caddis imitations, always consider the destination before you start filling up those little rows of slotted foam. The water type, season, local climate, and time of day will often determine which distinct hatches of caddis species you’ll most likely encounter. The most important characteristics in fishing a caddis hatch on a local piece of water are size and color; matching these characteristics properly can make or break a day of fly fishing.

Caddis are most vulnerable during their pupa and emergent stages, pupae, emerger, and cripple imitations will be the most important bugs to keep at the ready in your fly box. Because caddis instinctively spend very little time on or in the water after hatching to winged adults, caddis hatches are often disappointing to anglers looking to take trout on dry fly imitations of winged adults. For the very best dry fly fishing with caddis imitations, look for females returning to the water’s surface to deposit their fertilized eggs — trout will readily and aggressively take these sexually mature females and periods when females return to the river can mean fantastic results for well-prepared fly anglers.

Western state anglers should know that the caddis is commonly the dominant aquatic insect in most trout streams. Knowing this, an angler looking for more trout-catching success would do well to fish more caddis patterns. Although there are many ways to present a caddis pattern, there are two proven approaches: Since the majority of caddis are consumed sub-surface (below the water), it only makes sense that a fly fisher employ a nymphing technique. Whether high stick nymphing or indicator nymphing, taking your fly closer to the fish typically results in more hook ups. The second technique (and the most enjoyable) is the offer your caddis fly on the top of the water. Dry fly trout fishing is the essence of the sport of fly fishing and can be the most rewarding. There’s just something special when a trout rises to your caddis on the stream’s surface.

To enjoy caddis fly fishing (nymph and dry) we recommend you arrive prepared with the right gear:

Leland Rod Company’s New Zealand Trout Fly Rod

Leland Rod Company’s New Zealand Dry Fly Rod