Caddis Hatches of the Northeast

Order Tricoptera

Caddisflies are very important aquatic insects rivaling mayflies on many trout streams, particularly in tailwater and areas of low level pollution un tolerated by mayflies. On some rivers caddisflies are the primary food source. After the early season glut of mayfly hatches, caddis flies may be the only action available.

Fishing success is greatly improved by identification of the caddis activity on the water. Caddisflies may look alike but have very different habits of emergence and oviposting. To successfully fish the caddisflies, identification must be to the Family, genus or in some cases species level.

By knowing the genus/species of the caddis on the river, behaviors as well as appearance can be accomplished with your presentation. Although there are hundreds of species of caddis flies, most are not present on trout streams and many do not reach the numbers to justify importantance. To further simplify the subject, many caddisflies have similar appearance and habits within their family and genera.

Keys to identification

Metamorphosis Stages

Larval Stage
Caddisfly eggs are fertilized on shore then deposited in or adjacent to the river where they hatch into the larval stage which lasts 7 - 8 months.
Most larval species build a case in which they develop. These cases are distinctly different per family and are a valuable clue to identification.
Some species build a net to catch microscopic food.
Some caddisflies are termed "free living", hunting the bottom for food.
Trout eat all forms of the caddis; free living, net spinners and cased.
Pupal Stage
All caddis larvae build a case to begin their pupal stage where they complete their metamorphosis to adults. When fully developed, the pupa chews out of the case and makes its way to the surface to remove the pupal shuck. At this time, caddis are fully exposed and are most vulnerable to trout. Some pupa that never succeed in removing the shuck are termed "cripples". After removing the shuck, the adult caddis fly to stream side where they live several weeks preparing for mating.
After mating the females deposit their eggs in one of the following methods. After mating caddis adults fall spent to the surface available to the trout.

Determine the stage causing the feeding activity.
If the trout are feeding on the bottom, they are likely feeding on the larvae or pre emergence pupal drift.
Feeding just below the surface indicates emerging pupae.
Feeding in the surface film may be either pupae removing shucks or oviposting adult. A problem arises in determining which stage is causing the feeding activity. Both often occur at the same time by the same species and look the same to the fly fisher but the underwater profile is much different. Trout are selective to these stages.
Discarded pupal shucks may solve the mystery or trying both imitations may be necessary.

Fishing the caddis stages
Larval
Larva drift with head down tail up. This can be imitated by dead drift and/or twitching the fly slightly. A strike indicator may be used to control the depth of the drift.
Pupal
The pupal stage is usually the most productive fishing opportunity and offers three distinct methods of presentation. First there is the pre emerging drift of many caddis species which should be fished dead drift at the bottom. After this drift, the caddis swim to the surface imitated by a dead drift followed by lifting the fly off the bottom. Upon reaching the surface, the pupae struggle in the surface film to remove the shuck. An emerger pattern fished in the film with subtle twitching is called for here.
Oviposting adult caddis
Trout feeding on adult caddis that ovipost by repeated dipping on the surface offers the classic dry fly fishing. Cast directly to the feeding trout dead drift.
A pupa dropper on an adult pattern can be productive if having trouble determining which stage is causing the feeding activity. Some times both work.
For species that dive underwater to lay eggs, use and adult pattern pulled under to imitate the female returning to the surface.
Caddis fall to the water and die after completion of egg laying. The best time for this activity is after dark or early the next morning. Use an open winged pattern fished dead drift.

With the above information in mind, please visit the following list of the most common and important Caddis for the Northeastern USA.

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