Why and How to Fish Intruder Flies

Intruders were designed originally for steelhead like this one, but they also weor great on salmon and aggressive trout. Photo: Kubie Brown

The first time I used an intruder fly, it changed how I fish. It was on a steelhead trip in Washington, on a river I had never fished before, and I was having a hard time hooking up. Steelhead were in the river—I could see them jumping as they moved upstream—but my arsenal of classic and reliable steelhead flies just weren’t doing the job.

On my third fishless day, I ran into an older angler who asked me if I’d had any luck. When I told him I hadn’t, he asked to see my flies. “Too small,” he said looking at my box of hair-wing patterns. He pulled a plastic sandwich bag of flies out of his pocket and handed me two flamboyant-looking flies with small hooks dangling off them. “Try these,” he said.

That evening, I tied one of the old man’s flies on my line, and on my third cast, I connected with what turned out to be my first wild steelhead. After that trip, I became obsessed with the large, gaudy patterns that the old man had introduced me to: Intruders. I tied as many as I could, in as many sizes and styles as I could, because I figured out one thing that day on the river—Intruders catch fish.

Intruder patterns come in a variety of shapes, colors, weights, and materials. Photos via Red’s Fly Shop

What is an Intruder?

An Intruder isn’t a specific pattern. Rather, it’s a style of fly that’s tied on a shank or tube, with a stinger hook off the back. Generally, Intruders are made of bulky, flowing materials—such as fox fur, ostrich feathers, marabou, and even bucktail—that are sparsely tied to create a light fly with a large profile. Designed to be swung on a tight line, Intruders are meant to trigger aggressive strikes.

First created by legendary steelheader Ed Ward in 1993, Intruder flies were so named because they “intrude” on fish’s personal space to elicit a territorial response. Fish protect their chosen lies from the encroachment of others, especially during the spawn. Trout, salmon, and steelhead can be particularly aggressive during these times, especially when they’re migrating. They become extremely territorial and will lash out at everything from baitfish to other salmon and trout. An Intruder capitalizes on this behavior by invading a trout or salmon’s personal  bubble and eliciting a response.

Tying intruders requires a bit of finesse, as you have to find the right balance of flash and bulk to make the flies look natural, yet conspicuous enough to make them stand out and cause a fish to strike but not run away in terror. In addition, Intruders need to be large enough to create a significant profile in the water while still being sleek enough to make them easy to both cast and fish. This can make tying Intruders almost as addictive as fishing with them. With a creative mind, you can tie an intruder out of almost any material, with any color scheme you want. Often, this takes intruder patterns to an entirely new level, as innovative fly tiers have created patterns that pass beyond simple fishability and into beautiful works of art.

Materials that offer a lot of movement in the water trigger strikes from fish protecting their lies. Photo: Kubie Brown

When to Fish Intruders

You can fish Intruders for trout, salmon, and steelhead throughout the entire year. However, there are certain seasons, water conditions, and areas of the river when these flies are going to catch more fish. In addition, there are also specific species that are slightly more aggressive, making them more apt to smash an Intruder.

Fall is absolute prime time to fish an intruder. Spawning species—such as salmon and brown, brook, and bull trout—are more aggressive and likely to smash a large gaudy intruder. In addition, autumn is also the time when spring-spawning steelhead first enter rivers. Moving upstream like silver juggernauts, these fall-run fish can be extremely aggressive as they search for winter holding water, jockey for position, and chase other fish out of their area, making them ideal intruder targets.

Winter is also a great season to fish Intruders, especially when targeting winter-run steelhead. These giant fish rarely, if ever eat once they enter the river, and cold water can make them sluggish and not very willing to strike out at smaller flies. However, a gaudy intruder fly dangling right in front of their faces can cause these lethargic fish to lash out.

Other great times to fish an Intruder is in the early spring or any other time you’re fishing high or off-colored water. The fly’s large profile and obvious movement make it easy for fish to pick out in murky water when they can’t easily find other prey. In addition, spring is also the spawning season for rainbow and cutthroat trout, as well as steelhead, making the fish aggressive and very apt so smash large, flashy flies.

From fall through spring, swinging Intruders is a great way to cover water. Photo: Kubie Brown

How to Fish an Intruder

Swinging is the primary way to fish intruder flies. The pattern’s bulky design is ideal for covering water when you’re chasing aggressive salmonids who are willing to play, and the long stinger hook is perfect for connecting with short-striking or lethargic fish. Yet, Intruders don’t work in every type of water or for all fish.

Ideal intruder water is a deep, slow-moving run that is flowing at about a walking pace with a lot of changes in depth and structure spread throughout its length. These are the kind of runs that large predatory trout , salmon, and steelhead gravitate toward and hold in as they move upstream. Fishing these spots properly requires an Intruder pattern that will swing close to bottom, rather than through the center of the water column, so you’ll want patterns with a little bit of weight incorporated. For salmon and steelhead, I prefer larger, gaudier Intruders such as the Pick Yer’ Pocket or Senyo’s Artificial Intelligence. For large trout, I’ll use more natural looking flies like the Montana Intruder or Summer Sculpin.

To fish a deep, slow run, cast down and across at a roughly 45-degree angle, and then make a mend and allow the fly to sink. Next, tighten up on the line and allow the fly to swim across the river until it comes to rest directly below you. If you don’t feel like your fly is getting deep enough, cast directly across the stream to give the fly more time to sink before the swing.

It’s important to note that if you’re fishing for salmon or steelhead, the fly should remain steady as it swings with no additional movement, allowing the long flowing materials to do their job. However, if you’re fishing for trout, you can add in periodic flicks and jerks as the fly swings to trigger the more predatory trout into striking. (Click here for more on swinging speed and depth.)

The other ideal area to swing Intruders is through wide, fast runs with a lot of boulders, riffles, and pockets. Fish holding and moving through these areas are usually aggressive, and the large profile and flashy appearance of an Intruder swimming past their nose can infuriate them. When fishing in shallow, fast water, I prefer to use lighter patterns that still push a lot of water, such as the Hoh-Bo Spey, Senyo’s Stray Dog, and Predator Scandi.

Hoh Bo Spey
Hook shank: Waddington shank (here, a Partridge V1SS), size 25 mm.
Thread #1: Black, 6/0 or 140-denier.
Connection: Smoke Berkley FireLine, 30-pound test.
Hook: Intruder-style hook (here, a Partridge Z4), size 2.
Butt: Pink Ice Dub UV.
Flash: Gold Krystal Flash.
Body hackle: Dyed pink Guinea hen.
Body: Purple Ice Dub UV.
Collar: Black strung marabou.
Flash: Fuchsia SemperFlash holographic tinsel.
Horns: 6 dyed-pink Lady Amherst fibers.
Head: Tying thread.
Adhesive #2: Head cement, here Sally Hansen Hard-as-Nails.

When you’re fishing in these shallow, fast spots, work strategically. Instead of casting and swinging across the entire run, pick out small sections of likely looking water and work them individually. Focus on small pockets of slick-looking water where the fast and slow currents meet, as well as the front, back, and edges of boulders and other structure. Position yourself in the water so that you can cast, mend, and swing through these sweet spots, speeding up and slowing down accordingly.

I Don’t Mean to Intrude

Many anglers don’t like Intruders because they can be a pain to tie. They simply don’t want to put so much time and effort into a fly pattern that they may lose to the river bottom, especially when there are so many easier fly patterns out there. However, there’s something about Intruders that makes the time you put into creating them worth the effort.

When you tie an Intruder, you become involved with the fly. With every new material you add, creating a change in color or an extra bit of flash, you can almost visualize the fish that are going to react to and strike out at it as it swings. Intruder patterns are flies that allow you to delve deeper into a trout or salmon’s world to figure out what makes them tick and every time you tie one on your line, you learn a little more.