Boise Valley Fly Fishers
Since 1971


Bug Corner: Fall Caddis

30 Aug 2022 8:17 AM | Anonymous

by Troy Pearse

Fall is just around the corner and so is the Fall Caddis, also known as the October Caddis.   Fall Caddis are present on many of our local rivers, including the Middle and South Forks of the Boise river and there are even a few on the main Boise through town.  Larger populations of the Fall Caddis can be found on northern Idaho rivers including the Lochsa, upper North Fork of the Clearwater and the St Joe.  

Fall Caddis

Fall Caddis larvae live in a large pebbled case for one year. In late summer, they migrate to rocky edge-water, attach their cases and start to pupate. Hatches start in mid-September and go through October, and can continue into early November at lower elevations.  One tip for fishing the Fall Caddis is to look for these large caddis cases and make a note to come back and fish that spot in the Fall.  

Big bugs on the surface are always fun, and the Fall Caddis is no exception. My best Fall Caddis dry fly fishing is in the evenings, targeting structure along current seams near the edge of the river with rapid-fire casts and short drifts, sometimes twitching and hopping the pattern.  Trout takes are often explosive as soon as the pattern hits the water, so be ready!  During the day I use a heavily weighted pupa pattern for my anchor fly when nymphing.  Swinging a soft hackle pupa with your Trout Spey Rod is another effective technique, and also works well for steelhead on rivers where Fall Caddis are present like the Grande Ronde. 

I like a heavily hackled pattern for my dry fly. It's hard to beat an Orange Stimulator or orange Elk Hair Caddis.  I tie my Fall Caddis on a size #8 TMC 5212 2XL "hopper hook". Commercially tied Stimulators are typically tied on a 3XL hook, so if you are buying your flies you want to size down to a #10.  For a pupa pattern I like soft hackle patterns like Morrish's Deep October Pupa tied on a heavy nymph hook such as the TMC 5262.

For additional information on the Fall Caddis life cycle and some amazing pictures of them hatching at night, check out Arlen Thomason's book "Bug Waters", which is a bug-book every serious angler should own. Pay attention to his pictures of the pupal shucks and then look for them as you are fishing in the Fall and you will find a good spot to target with an Orange Stimi that evening.

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