2008 October 14 « SwittersB & Fly Fishing

Adult Dicosmoecus~SwittersB (Deschutes R.)

Given the size of the October Caddis, it does not take many to cause you to throw on a big Caddis dry. The hatch generally happens late afternoon and toward last light; it usually is not a large hatch. When you will typically see them though is during the day when they flutter from there resting place during the upstream winds; or, when they dabble along the surface laying eggs. Who doesn’t prefer to fish a dry, but as we are often admonished, you should, often, stick with the pupa patterns. Tans and greens with an orangish tint are nice pupa colors. In the Fall, these insects will tend to be in the shallows or edges having gradually moved from the faster waters via drift and crawl. Focus near the shorelines much as you would with stoneflies.

Harriet Caddis Pupa

Larva & Pupa Biology

Diet: Detritus (Detritus: Small, loose pieces of decaying organic matter underwater.), algae, dead animals
Current Speed: Slow water early; faster water in later instars (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.)
Shelter Type: Plant matter early; gravel in the later instars (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.)

The larvae are unusually prone to behavioral drift (Behavioral drift: The nymphs and larvae of many aquatic insects sometimes release their grip on the bottom and drift downstream for a while with synchronized timing. This phenomenon increases their vulnerability to trout just like emergence, but it is invisible to the angler above the surface. In many species it occurs daily, most often just after dusk or just before dawn.) during the daytime in June and July, usually around 4:00 p.m. They may be in between cases when they do this, making them especially appealing and visible to hungry trout.

In mid- to late summer they enter diapause (Diapause: A state of complete dormancy deeper even than hibernation. While in diapause, an organism does not move around, eat, or even grow. Some caddisfly larvae enter diapause for a few weeks to several months. Some species of microscopic zooplankton can enter diapause for several hundred years.) until cooler fall temperatures trigger them to pupate in a synchronized way.

http://www.troutnut.com/hatch/2594/Caddisfly-Dicosmoecus-Giant-Orange-Sedges