Fly Fishing Entomology 101 – Caddisflies

If Mayflies resemble small twin-engine airplanes, Caddisflies resemble B-52 bombers. The long wings of Caddis flies flank their abdomen, meeting at the top like the two slopes of a gable roof. This means Caddis patterns are easy to see on the water.

However, during the thick of a hatch, it’s hard to pick out your fly in the midst of dozens of other bugs on the surface. I’ve even had to scoop away Caddis adults that are crawling on my glasses, my nose, my hat, and my sleeves.

It’s no wonder that Gary LaFontaine called the Spotted Sedge Caddis the single most important trout-stream insect. I’ve caught fish on Caddis patterns from Wisconsin to Montana. Here is a brief profile of this important species:

Names

• “No matter what the subspecies, fly fishers simply refer to them as “Caddis.”
• “Caddisflies belong to the order ‘Trichoptera.’ Occasionally, books on flies and fly patterns simply refer to ‘Spotted Sedge’ — the most notable subspecies of Caddisflies for fly fishers.”

The Basics

• Most Caddisflies have a one-year life cycle. Once they emerge, the adults can live for as long as a month—as opposed to a couple of days for most Mayflies.
• Caddisflies, unlike Mayflies and Stoneflies, have complete metamorphosis, going from egg (1-3 weeks) to larva (9-10 months) to pupa (2-5 weeks) to adult (1-3 weeks).
• Entomologists divide Caddisflies into five groups based on the way their larvae behave. The five groups are: free living (no case or shelter), saddle-case (dome-shaped case with an opening at each end), net-spinning (a case with a web next to its entrance to catch food), tube case (portable case that enables the larvae to move around when threatened), and purse-case (a case of silk and fine sand).
• Spotted Sedge Caddisflies are net-spinners.
• According to Dave Hughes, trout probably eat more Caddis larvae than any of the other stages. Trout are likely to feed more selectively on pupae than on larvae or adult Caddisflies.
• Caddisflies hatch about any time of the day. To be sure, the 11 a.m. to 3 p.m. window is usually a given. But I’ve fished in Caddis hatches between 8 a.m. and 9 a.m. and as late as dusk—both in the Upper Midwest and in the Intermountain West.

Effective Patterns for Caddisflies

• Most fly fishers will concentrate on patterns that imitate the larva and the adult stages. But since Caddisflies (like Mayflies) can get “stuck” in their pupal shuck, the right pupa pattern can be effective.
• It’s best to check your local fly shop for the best larva pattern to use since there is such a wide variety of Caddis larvae. Some of the more popular patterns include the Tan Caddis Larva and the Olive Caddis Larva (both with beadheads). I’ve also used a Beadhead Red Fox Squirrel Nymph successfully in the Yellowstone River in Montana.
• Popular pupae patterns include the Deep Sparkle Pupa (either brown or yellow), the Krystal Flash Pupa, and the Beadhead Caddis Pupa. Fly shops will typically have a particular pattern that works well in the local waters.
• The most famous of all the adult patterns is the Elk Hair Caddis. This fly has tan elk hair, although we’ve used patterns with the elk hair dyed black in the Driftless region of Wisconsin and Minnesota. The body of an Elk Hair Caddis will typically be tan or green or (in some instances) black.
• The X-Caddis pattern, developed by Craig Matthews and John Juracek, is a great option for imitating adults which are caught in their pupal shuck.
• often tie a bit of red or pink antron body wool on the top of my Elk Hair Caddis pattern (see the above photo) so that they are visible to me when surrounded by a dozen other Caddisflies in the current.
• Sizes 12-18 are standard for all stages, although I’ve done the best over the years with sizes 14-16.

Other Entomology 101 Articles & Sources

THE PALE MORNING DUN

BLUE WINGED OLIVES (BWO)

Sources: Dave Hughes, Craig Matthews, Jim Schollmeyer, Bob Granger