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Monday, June 26, 2017

GTi Caddis


GTi Caddis
The GTi Caddis is more imitative than most of my patterns.  It represents a hydropsychidae larvae, commonly called "net builder" Caddis.  Though a bit cheesy, GTi stands for Go-To imitation.  This pattern truly is my go-to when wanting a weighted fly that closely imitates a favored large food form of Trout.  One thing you'll notice when comparing real Hydropsyche to my imitation is that the back on the GTi does not necessarily match any of the color combinations of the real insect.  This isn't by chance.  I've spent a fair bit of time tying and trying Caddis larva imitations and I've come to learn a bit about what fish prefer in the process.  For reasons unknown to me, Trout consistently prefer this fly when tied with a shellback color that contrasts the underbody.  I've tried many imitations that more closely represent the actual colors of Caddis larvae, but the fish do not take them as well.  There is something magical about the contrasting colors.  Try it, you'll like it...  One other thing about this and other weighted flies.  Keep them thin.  It's easy to make the body of weighted nymphs obese due to the layer of lead wire covering much of the hook.  Use dubbing materials that allow you to create a very thin dubbing noodle.  Less is more with dubbing.  Wrap it sparingly, but be sure to cover the lead and thread underbody.  Hareline Haretron is perfect for making thin, tightly wrapped nymph bodies.  Tie up a few GTi's with contrasting colors (see recipe below) and fish them in your favorite Trout water.  

If you don't tie, you can buy the flies directly here.

Material List

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Hook: Hanak H 300 BL Original Czech Nymph Hook - 12     
Thread: UTC Ultrathread 70 Denier - Olive     
Weight: Lead Wire Spool - .015     
Tail: Strung Peacock Herl     
Rib 1: Umpqua Tippet Material - 6X     
Rib 2: Krystal Flash - Olive     
Abdomen: Hare-Tron Dubbing - Olive     
Thorax: Arizona Synthetic Dubbing - Peacock     
Wing Case: Scud Back - Summer Duck - 1/8"     

Other tools from the tutorial:
Renzetti Master Vise     
C&F Design Bobbin     


  1. Lance, what choice of fly would you use on a river that has a large number of cased caddis? It seems the rivers around me are full of cased caddis, every rock I turn over has 100's of little cases stuck on them? Are fish even feeding on these caddis? Maybe only during a hatch? Thanks in advance.

  2. Trout will certainly take cased caddis, though I don't find them in stomach pump samples as much as I see them in the river. If you want to try a fly to imitate them, consider tying a frenchie with a chartreuse hotspot. Maybe even leave the tail off of the fly. Otherwise, my advice is don't overthink it. We tend to get wrapped up in match the hatch type patterns because it makes sense to us. Trout are opportunistic. Fish an attractor type of fly or something impressionistic like a hares ear or pheasant tail. A pattern that doesn't imitate a particular insect but has silhouette and size close enough to look like "food". Fish the fly in the proper water types and at the proper depth (or on the surface), eliminate drag and let the fish do the rest of the work.

    1. Thanks for the response. I know it is a very simple fly, but if you are looking for another video to do, I would love to see one on the tungsten surveyor with some background info etc. Just a thought.