Fly Fisherman Throwback: Understanding the Underrated Scud

Editor's note: Flyfisherman.com will periodically be posting articles written and published before the Internet, from the Fly Fisherman magazine print archives. The wit and wisdom from legendary fly-fishing writers like Ernest Schwiebert, Gary LaFontaine, Lefty Kreh, Robert Traver, Gary Borger, Joan & Lee Wulff, Vince Marinaro, Doug Swisher & Carl Richards, Nick Lyons, and many more deserve a second life. These articles are reprinted here exactly as published in their day and may contain information, philosophies, or language that reveals a different time and age. This should be used for historical purposes only.

This article originally appeared in the May 1983 issue of Fly Fisherman magazine. Click here for a PDF of the print version of "Scuds."

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Two fishermen wielding spinning rods were at the other end of the pond, perhaps 200 yards away. It was a clear, calm October morning, the Laramie Mountains dawn-silhouetted to the east, and in the assurance that distance brings, the two fishermen were discussing me as they cast into the deeper water.

"He'll have a hard time catching fish over there," one said. Arcs of gold flashed above the water as his spinner caught the morning sun.

"Yeah, water's too shallow and weedy over there," the other fisherman agreed.

Embarrassed, I stood thigh-deep in the pond. With the angry chauvinism of the newly-born fly rodder I was determined to show those two spin fishermen that I knew what I was doing, that I could catch fish. The trouble was, I didn't have the slightest notion of how to go about it.

I had one factor working for me: I knew fish were feeding just a few yards away. Every few seconds the swirl of a broad rainbow's back broke the water or the pinkish-white flash of a trout's mouth appeared as a fish took some unknown morsel.

In my innocence I supposed that some sort of hatch must be occurring. Since nothing was visible on the water I tied on the tiniest dry fly I had in my sparse selection, a #18 Mosquito. Slowly I worked my line out over the water until its flicking reached a relatively open spot in the thick weeds. The fly dropped onto the water and sat there, perched on its hackles. It remained there, too, while the water fairly boiled around it. The wake from one trout's swirl finally washed the fly under and I started to slide the line off the water for another cast.

As I raised the rod to start the backcast there was a sudden resistance. A stocky rainbow splashed clear of the water, ran for 10 feet and then jumped again, landing with a flat whack that broke the silent morning like thunder on a clear day.

"Son-of-a-gun ..." I heard one of the spin fishermen mutter. I didn't even glance at them, partially out of arrogance and partially because I was very busy, trying to tame that wild rainbow.

Finally I slid his tired body over the weedbed in front of me and hefted him in my hand. His stomach contents showed nothing that I immediately recognized–at that stage of my fly fishing career I would have been hard put to recognize a mayfly–just a mass of grayish material. I slid him into the creel and thought what the heck, I caught one on this fly, and started false-casting.

The fly alighted once more and rode unmolested above the busy water around it. Puzzled, I started to bring it back. It sank again, and was stopped almost instantly by another fish. This one disengaged himself from the fly on the first jump.

The still-fishless spin fisherman was more forceful. "Well, hell ..." came plainly across the water. I knew, however, that my fishing success wasn't the result of any great skill, and started to observe the water around me more closely. As I waded through the weeds clusters of tiny buglike things, not over a quarter of an inch long, fled in jerky, erratic spurts through the water. None that I observed had any vestige of wings, so I clipped the hackle from my Mosquito and fished it in short jerks over the weed beds. I lost a lot of fish that morning to weeds and the light leader I was using, but I landed and released about 20 rainbow trout, all fine, fat fish in the one- to two­ pound class. I heard no more comments from the other end of the pond.

Freshwater Shrimp

That was my introduction to the scud, a tiny and prolific crustacean common to many trout waters that some fishermen know as the "freshwater shrimp." There are indeed freshwater shrimp in American trout waters, but they are not nearly as common as scuds and hence not as common a trout food.

There are two main genera of scuds of interest to fishermen in American freshwaters, the small Hyalella, which averages one-eighth to one-quarter inch in length, and the larger Gammarus, which normally is about one-half to one inch long. Each comes in a variety of hues, primarily gray, olive, tan and creamy yellow.

The scuds in that Wyoming pond were a species of Hyalella, tiny gray scuds with the amazing name, knicker­bockeri. They're found from the South Platte of Colorado to Montana's Madison, in farm ponds and rivers, from low valley streams to high mountain lakes. And wherever Hyalella swims, he attracts trout like trout attract fly fishermen. Later that same fall I fished the North Platte near Saratoga, Wyo., and encountered the same variety of tiny gray scud. This time, however, I was prepared. In my fly vest was a small box full of #18 and #20 imitations, very simply tied, with gray thread for the body and a touch of webby hackle at the head and tail. A number of average rainbows and one brown over two pounds fell for the fly that day. I fished them in gentle, sweeping spurts in the slower river backwaters and became an instant fan of the scud.

Over the next few years I learned the tiny pattern's limitations, though. It is primarily an early and late-season producer, doing its best work when the insect hatches of summer do not distract trout, though there are exceptions to this. Its greatest successes have occurred in shallow water, because scuds tend to inhabit the shallow, weedy littoral zones along lakes and slow rivers. But perhaps the hardest part of scud fishing is reading the conditions.

Off and on for years Norm Strung and I have fished a spring-fed tributary of the upper Madison early in the spring. There is a section of the stream that is slowed by a decrepit dam, the legacy of an old sawmill. The stream flows smoothly, in a Montana imitation of a chalk stream, perhaps 50 yards across, for a quarter of a mile above that dam, the depth reaching six to eight feet. From a boulder that lies in the stream I've seen brown trout of four and five pounds cruising slowly and feeding in the glassy water. We have fished that section of the stream with every imitation known to man and though the fish were always actively feeding at that time of year, we were rarely very successful. It wasn't until two years ago that its secret unfolded.

It was a foggy, cool day as we rigged our rods next to the stream. Swirling rises appeared like slow rain fall on the smooth water, dreamily drifting downstream under the fog. The fish were rising purposefully, assuredly, and I assumed that a midge hatch was in progress, a common occurrence on those waters. Both Norm and I cast tiny dry midge imitations for 20 minutes before I switched to a midge nymph, guessing that the fish were taking emerging midges as they rose to the surface.

Often I've been afflicted with a slow angling mind. It wasn't until I'd actually hooked and released a small brown that it suddenly came to me. I waded deeper into the stream, kicking the newly-emerged vegetation. Tiny gray scuds darted out in clouds. I left the water and climbed the bank-from that vantage point I could see that fish were not only swirling near the surface in what had appeared to be rises but were feeding at some depth.

Quickly I tied a three-foot section of 6X tippet to my already-long leader, then one of the #18 scud imitations. Casting slightly upstream, I waited for the scud to sink a foot below the surface before bringing it back with a brisk hand twist. The first swing brought one take, which I struck late, and then another small brown which I hooked after its mouth flashed in the dark water.

"What are they taking?" Norm shouted from his perch atop the boulder 50 yards downstream. I told him and he tied on his closest imitation and for the next two hours we regularly took fish up to two pounds. My rod was a little too stiff for the light leader, and I broke off two or three larger fish on my anxious, keyed-up strikes.

That stream exhibited nearly ideal scud conditions, which I would instantly recognize today. It rises from limestone substrata and hence is highly alkaline, which is not a necessity for Hyalella but a fine indicator. Its flow is slow and even year-around, which encourages the vegetation that scuds live in and partially feed on. On top of that it was a cool spring day, which discouraged the insect hatches that might have distracted the trout.

I've also encountered Hyalella in beaver ponds on acid streams, but they are more numerous, and their imitations more productive, in alkaline environments.

The Big Scud

The larger Gammarus genus, however, is almost always found in alkaline waters. Gammarus are not as common in the West as the smaller variety, but their size makes them very attractive to trout wherever they are found, though they require different fishing techniques as a rule.

High in the Montana Rockies is a deep reservoir full of two- to four-pound cutthroat. The waters that feed it rise in typical Rocky Mountain granite-and-limestone formations, and are rich in the calcium that Gammarus scuds require for the formation of their exoskeletons. The best fishing in the reservoir occurs in early summer when the fish are spawning. The upper end of the lake is laced with the deep channels of feeder streams and the fish gather there in the slight current, feeding both on Gammarus scuds and caddis nymphs.

Fishing is best early in the morning, and so the last time I fished there the early gray light of dawn found me standing in the cold water along one of the feeder channels. I tied a large gray Woolly Worm to the leader on an 8-weight sinking line. I worked the water with long casts from a stout 8½-foot rod, and counted from 10 to 15 seconds at the end of each cast to allow the big fly to sink deeply into the channel. I lost one fly to a drowned spruce before the sudden, magical live weight of a fish straightened the line. The cutthroat stayed deep, fighting hard, pulling and pulling, keeping the 4X leader on the edge of its strength, before finally bulging the surface in a last flurry. It was a male of about 3½ pounds, the bright orange slashes under his jaw brightened by the peak of spawning. His stomach contents were about equally divided between large gray Gammarus and yellow-olive caddis, but the Woolly Worm acting as a scud took far more fish that day than any caddis pattern that my companion and I tried.

The Gammarus I've encountered in the West almost always have been in deeper water than the smaller Hyalella, and normally require the sinking-line technique, though occasionally they can be used on floating or sink-tip lines in some large spring creeks. I am of the general-impression school of fly-tying, partly because tying flies–after I've worked out a new pattern–bores me to tears, and partly because a few versatile patterns mean less weight in my fly vest. I've found simple gray Woolly Worms in sizes #4 to #8 on 1X-long hooks have worked in any Gammarus situation I've found in the West, though I've talked to other anglers who've encountered other varieties, especially the tan species. Eastern anglers should find olive and cream varieties useful in slightly smaller sizes. Occasionally I'll trim the hackle from the top of the fly, but it's rarely been necessary. They aren't weighted either, because I believe that weighted flies tend to have an unnatural, up-and­ down motion during a jerky retrieve and tend to catch fewer fish. In normally slow scud waters, a medium density sinking line is more than enough to take them down to fish level.

I tie the Hyalella imitations on #18 and #20 hooks. Again, the gray variety is most common, but I've encountered both olive and cream specimens throughout the West. I usually tie them either with built-up thread bodies or just a touch of dubbing, usually wool. Any extra detail long ago left these patterns, and I haven't found that it makes much difference to the fish. I've also experimented with a similar pattern tied with gray 6X leader material. It's designed for bright days, when the translucency of the monofilament may be more attractive to fish than opaque patterns. I haven't had the opportunity to use it much yet, but it has worked the few times I have tried it.

The smaller imitations require fine leaders, and my favorite rod for them is a soft 7½-footer that won't pop slender tippets on a quick strike. These tiny scuds are normally fished a foot or so under the surface, or even shallower over weed beds, with a floating line and a 12-foot leader, but occasionally a sink-tip line is necessary to get them down to fish-depth.

These imitations are most effective early and late in the year, but they're in my fly vest year-around–scuds can be encountered anywhere, anytime. Two summers ago, while hunting sharptail grouse on eastern Montana's plains, I became intrigued by stories of big trout in a farm pond nearby. A friend who lived nearby and I made an after­ noon trip, to find a weed-choked pond characteristic of those calcium-carbonate-rich prairie soils. My companion explained that the Montana Fish & Game Department each spring stocked the pond with fingerlings which rapidly grew into 12- to 14-inch fish by early fall. There were also many holdover trout in the pond of two pounds and up.

There was a mayfly hatch in progress, but these visible insects were being ignored. The conditions looked ideal for scuds, so I first cast a Hyalella imitation over the weeds. The second retrieve brought a one-pound rainbow to the fly. The fish leaped a half-dozen times, as strong as any wild fish I've ever hooked. A few casts later a two-pounder took 30 feet of line, leaped, and took 30 more before he could be brought under control. Both were full of scuds and had the firm deeply red-orange color characteristic of trout grown on scuds. I began to gain a new respect for stocked trout prairie ponds, and dimly recalled an old Ted Trueblood article that said the hardest-fighting inland trout he'd ever encountered were in ponds like this. The pond also brought back memories of that stocked valley pond near Laramie where I'd first encountered scuds.

We fished the rest of the afternoon, taking strong, hard­leaping fish every few minutes. Late in the day I struck a fish I instantly realized must have survived several prairie winters. He ran for the other side of the pond as if the buzzing reel didn't exist, then jumped once over there, his palm-width side silver in the sun, before turning and dashing for the weedbed in front of me. I reeled as fast as I could, but knew the effort was futile. When the line came taut it was buried in the weedbed, and there was no feeling of life left in the rod. I broke the fly off and stood for a moment, slightly shaken, vowing that the scud and I would return someday.

A Proven Pattern

By Dave Engerbretson

If I had to choose one type of fishing with which to occupy the rest of my days, it would be trout fishing on a cool, clear limestone spring creek with an occasional venture to a lake with the same type of water. Such alkaline waters are rich in insect life, the trout in them grow fat and strong, and they often prove to be the ultimate angling challenge.

Should I be fortunate enough to be consigned to such idyllic waters, my fly box would contain a broad assortment of scuds.

Ranging in size from under a half inch to well over an inch long, these little creatures actively swim and drift about the tops of the weed beds, and make easy pickings for trout. At times mass scud ''drifts'' occur in spring creeks as thousands of them let the current carry them downstream. At such times the fishing can be almost beyond belief.

Anglers who regularly fish spring-fed lakes or streams are missing a good bet if they don't carry a large supply of scud patterns. A number of patterns are effective, and they range from simple fur-dubbed creations to more highly involved ties. The pattern I prefer takes a middle-of-the-road approach. Simple to tie, it is at the same time realistic, and best of all, it has produced extremely well for me.

A hook of the appropriate size to match the naturals is first bent to a slight hump-backed curve and weighted with fuse wire. Don't over-do the curve, since the scuds swim in a straight position.

Tie in a rib of dark-grey buttonhole thread (or finer thread for the smaller flies) near the bend of the hook, and follow this by tying in a narrow strip of grey Swiss Straw or clear plastic-bag material at the same point the rib was tied in. Then secure a medium-blue dun hackle by the butt near the bend of the hook just ahead of the materials previously tied in. Dub a soft fur under-body over the length of the hook shank. Colors range from gray to olive, to pinkish olive, to dirty yellow to tan.

Naturals can be caught easily by pulling up a small clump of weeds from the bottom–you'll probably be amazed at the number you'll find. Look at the body color and try to match it with your artificials.

After dubbing the under-body, palmer the hackle forward over the entire length of the hook and tie it off. Fold the Swiss Straw forward over the back and sides of the under-body. This step should cause the hackles to fold down and project under the fly to form the legs. Tie off the shell, and rib with the thread previously tied in at the bend of the hook.

Finish off the fly with a rather large head, and pull several of the leg fibers forward from the head to form antennae.

Since scuds often swim backwards, some fly tiers like to reverse the fly on the hook in some of their imitations. But the little crustaceans swim both forward and backward, as well as on their sides and upside down, so I generally just tie them in the manner described.

The technique for fishing the scuds is quite straight forward. The most important consideration is to be certain that the fly has reached the proper depth before beginning your retrieve-just about even with the tops of the weeds. Often this can best be accomplished with the count-down technique. Start a count as the fly hits the water, and wait until you think it has reached the right depth. If the fly fails to tick the weeds occasionally on the retrieve, count a little longer before retrieving your next cast.

Since the scuds are active swimmers, a variety of retrieves can be effective–try a slow hand-twist technique, or give the fly erratic little strips, let it sink, and twitch it again. In moving water, a dead drift can often be effective. The key is to experiment, after being certain that the fly is at the correct depth. When you've got it right, the trout will let you know immediately!

Scud Pattern Recipe

• HOOK: #18-8, 1 to 3XL to match the natural (Bent to slight curve and weighted)
• THREAD: Gray
• SHELL: Gray Swiss Straw or clear plastic bag material
• RIB: Dark grey buttonhole thread (Finer thread for smallest flies)
• UNDER-BODY: Fur the color of naturals (olive, gray, pink/ olive, dirty yellow, tan)
• HACKLE (Legs): Medium blue dun, palmered over under-body and folded down by the shell
• HEAD: Large with a few hackle fibers pulled forward from the top to form antennae

John Barsness is a freelance writer living in Missoula, Mont. This is his first contribution to Fly Fisherman.

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