A simplified March Intruder tied with just three materials — marabou, Flashabou, and guinea fowl hackle — is one of the most effective and efficient flies for high, cold steelhead water. Built on a 35 mm shank with a trailing stinger hook, this streamlined version of Ed Ward’s original 1990s pattern takes under ten minutes to tie, costs a fraction of the $5 retail price per fly, and delivers the same pulsing, water-pushing profile that provokes reaction strikes in off-color flows from the Olympic Peninsula to the Great Lakes.
Best Colors for March Intruder Flies
Three color combinations cover the range of March steelhead conditions. Black and blue is the first-choice pattern for dirty water and low light — black provides a hard silhouette while blue adds contrast that consistently triggers strikes in cold, cloudy conditions. Jay Nicholas, the Oregon steelhead authority, ranks this combination as top-tier for winter. Purple and pink works as a late-winter alternative when fish have seen dark flies and need a different stimulus; the purple carries low-light visibility while pink adds an egg-like hot spot. Olive and copper is the contrarian pick for clearing water, pressured fish, or Great Lakes tributaries where steelhead key on baitfish like alewives and gobies — a drab, naturalistic profile that outperforms gaudy patterns when conditions shift.
All three use the same formula: marabou in the primary color, four to six strands of Flashabou in a matching or contrasting shade, and guinea hackle either natural or dyed to suit.
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Weighting and Rigging the March Intruder
The critical rigging decision is how to balance fly weight against sink tip density. An unweighted Intruder paired with a heavy sink tip — 10 feet of T-14 on a 525- to 575-grain Skagit head — gives the best action on big Pacific Northwest rivers, letting the fly undulate naturally while the tip provides depth. Ed Ward and Jerry French both favor this approach for high-water swinging. On smaller Great Lakes tributaries fished with lighter switch rods and polyleaders, add a tungsten conehead or medium dumbbell eyes so the fly can reach the strike zone without a heavy tip.
The trailing hook rig uses a loop of 30- to 50-pound fluorocarbon tied at the rear of the shank. Fluorocarbon’s stiffness holds a size 1 or 2 octopus hook in position directly behind the fly, preventing fouling and improving hookup ratios on short strikes in cold water. This shank-and-stinger design, which Ward pioneered, boosted landing rates from roughly 10–15% on long-shanked hooks to 85–90% with small trailing singles.
Fishing the March Intruder in High Water
Keep the leader short — three to four feet of 10- to 15-pound fluorocarbon from the sink tip to the fly. A longer leader lets the fly ride up out of the zone. Cast across, throw a big upstream mend to sink the tip and fly, and swing slowly. In 40°F water, steelhead won’t chase far but will crush a fly that drifts broadside through their lie.
On the Olympic Peninsula — the Hoh, Sol Duc, or Bogachiel — run T-14 tips and unweighted or lightly weighted flies when flows are between 3,000 and 6,000 cfs. On Great Lakes rivers like the Pere Marquette or Salmon River, scale to an 11-foot switch rod with T-8 tips. Don’t default to the biggest fly you can tie — California guide Jason Hartwick notes that most veteran steelheaders fish 2- to 4-inch patterns in winter with no drop in success. A 35 mm shank dressed sparse puts the fly right in that productive range.
Stock a dozen in three colors before March, and you’re ready for whatever window the river gives you.
How big should a March Intruder be?
Most effective March Intruders are 2.5 to 4 inches long. A 35 mm shank with sparse marabou and guinea hackle produces a fly around 3 inches — large enough to push water in turbid flows but small enough to cast cleanly on a 7- or 8-weight Spey rod. Oversized 5- to 6-inch flies often hinder casting more than they help attract fish.
What hook size works best for an Intruder stinger?
A size 1 or 2 short-shank octopus hook, such as a Gamakatsu Octopus or Owner SSW, is standard. Up-eye hooks ride more naturally on a loop rig and reduce weak points in the connection. Always fish barbless to comply with most steelhead regulations and improve fish survival.
Can I swing Intruders on a single-hand rod?
Yes, though a two-handed rod is far more efficient. An 11- to 13-foot Spey or switch rod paired with a Skagit head throws large flies and heavy sink tips with less fatigue. On smaller Great Lakes streams under 60 feet wide, a stout 9-foot 8-weight with a fast-sinking polyleader can cover adequate water.
When is the best time to swing Intruders in March?
Fish the warmest part of the day — typically late morning through afternoon — when water temperatures peak and steelhead are most willing to chase a swung fly. Focus on dropping flows after storm events, ideally when visibility reaches two to three feet and the river is trending down from its peak.
Do I need expensive materials to tie effective Intruders?
No. Marabou, Flashabou, and guinea fowl hackle are all inexpensive and widely available. A single package of each material ties dozens of flies. Skip exotic feathers like ostrich or rhea — marabou produces comparable movement at a fraction of the cost, and many guides’ most productive Intruders are deliberately simple ties.
