The Cased Caddis

A finicky rainbow trout ate my cased caddis.

The cased caddis is one of the most intriguing and dependable aquatic insects in a trout stream.  Colorado has a diverse range of caddisfly families, the order Trichoptera, with Limnephilidae, the tube-case makers being the most prevalent.  This diverse group builds case making to its uppermost development both in running water and stillwater. 

These larvae fabricate and dwell within portable casing of streamlining, structural rigidity, camouflage, internal water circulation and external water resistance protection from predators.  A cased caddis larva has a black or brown hardened capsule head, a worm-like segmented body, and six legs near the head.  Cased caddis are most often slow crawlers, clinging to rocks in riffles and runs of streams.  Larvae gather materials from their environment of fine pebbles, sand, leaf materials and bind them with silk into a cylindrical tubular shaped case and their way to anchor themselves to the stream bottom.  Unlike free-swimming caddis larvae, they stay tucked inside their case for protection from predators and current.

Natural colors of olive, gray, tans, and browns.

The tube-case makers feed and shred leaf materials, dead wood, scrap algae, and prey on other aquatic insects.  Most of the shredders dwell in headwater streams where trees canopy over water and quantities of leaves fall and sink intact.  They utilize this food form for the wood materials for the energy they derive from the associated micro-organisms, the fungi and bacteria that are consumed in the process.

For the trout, cased caddis is a year-round, high protein, sizable meal.  It is a fly pattern an angler may desire to keep in their box as another offering especially with springtime and increased flows when cased caddis are loosen and tumbling in the current.  Weight is key in hugging the bottom with fishing.  If you have not fished a cased caddis pattern, give it a try.  You just maybe surprised!

Larvae gather materials from their environment of fine pebbles, sand, leaf materials and bind them with silk into a cylindrical tubular shaped case.

When it’s time to metamorphose, they will secure their case.  As a pupate inside, they will surface thereafter as a winged adult caddisfly.  At the completion of the larval existence, the cycle progresses steadily through pupation, emergence, and egg-laying activities, creating the next generation in the streams and lakes.

Cased Caddis eat.