Three caddis dry fly patterns — Elk Hair Caddis, X-Caddis, and CDC & Elk — cover the three feeding windows that define May caddis fishing across the country: high-riding adults, emergers trapped in the film, and the low-profile silhouette pressured trout require. Each pattern was designed by a named tier to solve a specific problem, and together they work from the Mother’s Day Caddis on the Madison at 52°F to Driftless spring creeks in full afternoon sun.
The Three Patterns and What Each Does
The Elk Hair Caddis, designed by Al Troth and popularized through a 1978 Fly Tyer article, is the high-floating workhorse. Palmered hackle over a dubbed body keeps the fly riding above the film through skitter, strip, and dead-drift presentations. Tie it on a TMC 100 in sizes 10–18 with brown 8/0 thread, fine gold wire rib, hare’s-ear dubbing, and a stacked elk-hair wing.
The X-Caddis, designed by Craig Mathews, solves refusals to high-floating flies. The trailing Z-Lon shuck imitates a caddis whose emergence has stalled in the film. No hackle. Body is Zelon dubbing in olive, tan, amber, or black. Wing is natural deer hair. Tie it on a TMC 100 in sizes 12–22. Mathews states the pattern “works much better than standard ties like the Elk Hair Caddis” when trout are keyed to emergence.
The CDC & Elk, designed by Hans Weilenmann as a deliberate rework of Troth’s EHC path, uses a whole CDC feather wound forward for the body, with a deer-hair wing for flotation. Weilenmann frames the pattern as offering “illusion of movement” — the trait pressured fish respond to. Tie it in sizes 12–20 on a TMC 100 or debarbed equivalent.
When to Fish Each Pattern
Reach for the Elk Hair Caddis when rises are splashy, water is fast or broken, and visibility at distance matters. This is the Mother’s Day Caddis pattern when adults are active on the surface.
Switch to the X-Caddis when you see Craig Mathews’s three diagnostics: no visible insects on the water despite obvious feeding, splashy or porpoising riseforms, and concentrated feeding in fast water at the heads of runs. That combination means trout are eating emergers, not adults.
Tie on the CDC & Elk on flat water, with pressured fish, when bulk becomes a liability. CDC is tunable: grease it with a gel like Dry Magic to fish higher, or leave it naked to fish lower as a cripple — a dual-mode flexibility the other two patterns don’t offer.
Sizes, Hooks, and Colors for May
Across the Deschutes, the Yellowstone, and the Driftless, the core May size band is #14–#16, with exceptions. Big Y Fly Co’s Deschutes hatch chart lists grannom at #14 and gray caddis at #16 from May 1–15, with tan caddis at #14–16 running mid-May into July. Micro-caddis down to #20 are present on some Western waters and require the same patterns tied smaller.
On Mother’s Day Caddis events, multiple Montana outfitters recommend a 9-foot 4X leader and fishing one or two sizes larger than naturals for visibility. On flatter water with sipping fish, extend to 10–12 feet and drop to 5X or 6X.
A Deliberate Three-Fly Box
Three patterns — not ten — give you coverage across every May caddis scenario worth planning for, from the first Mother’s Day Caddis pulse through the mid-May net-spinner transition. Tie each in the sizes and colors your home water demands, and leave the rest of the shop selection for very specific waters and situations.
Frequently Asked Questions
What are the three best caddis dry fly patterns?
The three caddis dry fly patterns that cover most May situations are the Elk Hair Caddis, the X-Caddis, and the CDC & Elk. Each targets a different feeding window: high-floating adult, emerger trapped in the film, and low-profile adult for pressured fish. Together they cover the bulk of caddis activity on U.S. trout waters.
What size caddis dry fly should I use in May?
Most May caddis hatches call for dry flies in sizes #14–#16, with #18 and smaller for micro-caddis situations. On the Deschutes, grannom is typically #14, gray caddis #16, and tan caddis #14–16. In heavy Mother’s Day Caddis events, sizing up to #12 for visibility has field precedent from Montana outfitters.
What hook should I use to tie caddis dry flies?
Use a TMC 100 or equivalent standard dry fly hook (1X fine wire, wide gape, down eye) for all three patterns. Sizes 10–22 cover the full caddis range. Barbless variants like the TMC 100SP-BL are equally suitable and widely available at roughly $9.95 to $14.25 per 25-pack.
Can I substitute deer hair for elk hair in an Elk Hair Caddis?
Deer hair substitutes cleanly for elk in the Elk Hair Caddis. Orvis explicitly notes the substitution is common and does not change the pattern’s effectiveness. Fine-tipped deer hair is also the specified wing material for Hans Weilenmann’s CDC & Elk, so tiers working with deer hair on one pattern already have what they need for another.
Should I use floatant on CDC flies?
Whether to use floatant on CDC is a legitimate editorial disagreement. Hans Weilenmann argues paste floatant collapses CDC’s microstructure and destroys the feature that makes the material work. Charlie Craven recommends greasing CDC with Dry Magic to fish the fly higher, or leaving it untreated to fish lower as a cripple. The practical answer: match your treatment to the water, and know you’re choosing.
