Why Trout Eat, and Why They Don’t
When the Hendrickson hatch is at its peak on my New England streams, the insects blanket the water. Tens of thousands of pert little sailboats come drifting on the surface, and every trout in the pool is up and slurping. This would seem to be the classic setup for match-the-hatch dry-fly fishing, but in my experience, the angler with a precise Hendrickson imitation on the end of his tippet is doomed to frustration. Your best approach is to isolate a single riser, take a position upstream and to the side of his lie, and repeatedly drift your fly downstream to him. But even that tactic generally fails. There are just too many real bugs on the water. The odds are stacked against any fish deciding to eat your fake one.
It’s interesting to pick out a single trout and watch how he behaves during a blanket hatch. He sets up in the current, and even though he doesn’t need to move an inch to have a shot at a steady stream of floating duns, he marks out perhaps a 2-foot-by-2-foot square of territory, and he slides up and down and side to side in that square, picking off the occasional mayfly. He selects to eat just one out of every several dozen bugs that enter his territory.
You can’t help wondering about all those natural insects that this trout rejects. What’s wrong with them? What’s so special about those that he does choose to eat? How can an angler hope to catch this ultra-selective trout? Does it really have anything to do with the shade of pink on the fly’s abdomen, or the number of tails, or the angle of the wings? Is it all about the fish’s feeding rhythm?
After you’ve shown this trout your entire assortment of Hendrickson dun imitations, you might decide to try something different, on the theory that no imitation can look as edible as the real thing to this fish that snubs a lot of real things. Maybe a cripple, or an emerger, or a soft hackle, or a floating nymph will appeal to the opportunist in this fish. More out of frustration than because I had a sensible plan, I’ve sometimes ended up fishing a beetle or an Adams or a Royal Wulff to Hendrickson hatches. I’ve caught the occasional trout that way, too. More than once, in fact, a trout has taken my mis-matched fly on the first or second cast, and I’ve thought, “Aha! I have discovered the secret.”
Usually the next fifty casts with the magic fly produce nothing further.
When there is no hatch, we fish with what we call “searching patterns,” buggy-looking flies that resemble fish forage in general without necessarily imitating any specific food item. The Adams is a standby. So are the Elk Hair Caddis, and Pheasant Tail and Hare’s Ear nymphs, and soft-hackle wet flies, and Woolly Buggers. They are generalized patterns that, when presented in a lifelike manner, look a lot like many different things that drift down trout streams. We think trout mistake them for something that’s good to eat, even if they don’t know exactly what it is.
Another kind of searching pattern does resemble something specific that, we believe, looks familiar to trout, and they will therefore eat it even if they are not feeding actively on that forage item. Terrestrials, for example. Streamers that imitate sculpins or crayfish. Stone fly nymphs.
Some flies are categorized as “attractor patterns.” Royal Wulffs, Trudes, Stimulators, Humpies, Chernobyl Ants, Turck’s Tarantulas, not to mention purple bunny streamers, red-and-white Zonkers, and Mickey Finn bucktails—flies that aren’t even intended to resemble any natural trout food.
Attractor patterns, according to the theory, “attract” trout not because they look like something familiar and edible (because they don’t) but because they arouse some kind of emotion in the fish. Emotions often attributed to trout are curiosity, anger, playfulness, seductiveness, bellicosity, and territoriality. Because trout do not come equipped with hands, fingers, or fists, they use their mouths to express themselves. When they bite down on an attractor pattern, they are not eating. The emotion they’re responding to, according to this theory, is something other than hunger. When you tie on an attractor, your intention is to tease, seduce, or anger a trout into taking it into its mouth.
Harold Blaisdell, in his important book, The Philosophical Fisherman, explains it this way: “It is my belief that, in most cases, fish strike non-imitative lures for the same reason that a frog will jump for a red rag… They do so, not as the result of normal impulses, but because of stimuli so strange that they provoke indiscretion.
“It can be argued that it is more important to know what lures fish are likely to hit than to understand why they hit them. Certainly, it is to a fisherman’s advantage to be familiar with effective lures, but I think it is of even greater importance to understand the true reason for their effectiveness.
“Fishermen who use lures with the idea of provoking and arousing fish to the point of recklessness will employ shadings and touches of manipulation different from those used by fishermen trying to imitate bait fish with the same lures. And I feel certain that fishermen in the first category will take more fish.…
“What I have said about spoons and wobblers I believe to be true in large part with respect to plugs, bugs, spinners, streamers and wet flies that are worked or agitated. Although the success of all these lures is quite generally attributed to their imitative qualities, this claim seems extremely farfetched. Superficial inspection and observation will reveal that they resemble nothing else under the sun in appearance, and the lifelike action that they allegedly manifest is not even an approximation of the real thing. Their success, I believe, rests in their unique ability to excite fish to a state of belligerence quite beyond the control of their normal powers of discretion.”
This is what we think we know about why trout eat what they eat, and why they reject what they reject: They feed selectively, or they feed opportunistically, or they use their mouths to express their emotions. Our choice of flies and tactics is based on whether we think the fish are feeling selective or opportunistic or emotional at the moment.
The problem with this entire line of thought, of course, is that we have no idea what trout think or feel. It is the height of anthropomorphism to assume that fish experience anything remotely resembling what we humans know as anger, for example. When we use terms like “selective” or “opportunistic” or “belligerent,” we’re not really explaining the fish’s behavior—we’re simply describing the way it looks to us.
There’s no good reason to assume that trout have feelings at all, never mind feelings that are similar to human emotions. It’s quite likely that trout don’t “think,” if by that we mean that they use their brains to sort out the variables in their lives, to speculate about their futures, and to devise plans for solving their problems. Trout exhibit an array of behaviors that have evolved over eons to enable them to survive as individuals and to procreate their species. It’s safe to say that these behaviors are instinctive, perhaps refined by some life-experience conditioning—but not the product of reasoning. The trout’s brain does not intercede between the sudden appearance of a fisherman’s shadow on the river bottom and the fish’s quick dart to deep sheltered water. Nor does the trout think about what it selects to eat or to pass up. It reacts.
Thomas McGuane, in The Longest Silence, understands the trout’s selectivity this way: “In my view, a trout that is feeding selectively is doing the following: having ascertained that many of the objects going by his view are edible, he decides which ones he can eat efficiently and which will do him the most good. Then, in the interest of energy conservation, and if the chosen food item is in sufficient quantity, the trout gradually transfers the decision-making process to something like muscle memory, to thoughtless routine. If the fly we cast fails to trigger that recognition or is not in the rhythm in which the trout is feeding, we get a no-sale.”
I think McGuane is right about “muscle memory” and “thoughtless routine,” but I’m pretty sure that trout “ascertain” and “decide” things differently from the way we humans do, just as they feel “anger” and “belligerence” and “fear” differently from us, if they feel those emotions at all.
Ed Zern, who for many years wrote the bac
k-page column, “Exit Laughing,” for Field & Stream, gets the last word on the subject of why trout eat what they eat and why they reject what they reject: “Of course, every once in a while a fly fisherman catches a trout on a trout fly, and he thinks this proves something. It doesn’t. Trout eat mayflies, burnt matches, small pieces of inner tube, each other, caddis worms, Dewey buttons, crickets, lima beans, Colorado spinners, and almost anything else they can get in their fool mouths. It is probable they think the trout fly is some feathers tied to a hook. Hell, they’re not blind. They just want to see how it tastes.”
When Trout Get Antsy
Aquatic insects, in their many and varied species and in all the stages of their life cycles, provide food for trout and hatch-matching problems for anglers. Sometimes it’s deliciously challenging. Frequently, though, it can be downright infuriating, as Elliot Schildkrout and I discovered one hot August day on a big western trout river.
The morning spinner fall had come on schedule, shortly after daybreak. But it fizzled out under a blazing Rocky Mountain sun, and by midmorning it seemed as if every trout in the river had gone back to bed. We rowed slowly downriver, scanning the water for rising fish. Finally we spotted a few noses poking through the slick currents that the river funneled against the base of a high bluff. We pulled the driftboat against the bank.
“Oh, yeah,” whispered Elliot reverently. “Look at that.” Dozens of trout were sipping quietly tight against the steep bank. When we looked at the water, we saw Trico and Baetis duns and spinners; black, speckled, and blond caddis flies; Yellow Sally stone flies; and several species of midges drifting on the surface. It was a trout smorgasbord.
“What do you think they’re eating?” I said.
“Anything,” said Elliot, already climbing out of the boat. “Everything. It’s a buffet. Let’s get ’em.”
We fished side-by-side, changed flies often, called the fish colorful names, and raised no trout, although they continued to feed off the surface—sometimes within millimeters of our imitations.
After a while I accepted defeat. I reeled in, climbed into the anchored boat, and took a sandwich and a jug of lemonade from the cooler. While I ate, I watched Elliot, more persevering than I, continue casting, changing flies, and mumbling. Bugs kept crawling on my face, and I brushed them away. One got in my mouth, and when I spit it out, I must have muttered a curse, because Elliot turned and said, “What’d you say?”
“Damn ants,” I said. “They’re all over the boat, in my face, on my sandwich.”
“Ants, huh?”
The next thing I knew, his rod was bent and his reel was screeching. He landed the trout and a moment later had another one on. That’s about when I figured it out.
Ants. They ruined my picnic, but they were the trout’s banquet.
We should have known. Whether they’re rising selectively to a hatch of aquatic insects or gobbling opportunistically at whatever comes their way, trout rarely refuse to eat the odd ant that drifts over them. A good trick to taking selective fish during a heavy mayfly hatch is to show them an ant imitation. Even when they’re not rising at all, you can often take trout on a floating or wet ant pattern. The ant is the closest thing to an all-purpose trout fly that I know.
If you look closely, you’ll see ants crawling on virtually every square foot of land in the world where trout streams flow, so it’s not surprising that ants drift on every brook, spring creek, tailwater, and freestone river in North America. They continually fall or get blown onto the water. Midges, mayflies, stone flies, and caddis flies come and go. But trout see ants all season long, and they eat them constantly.
Anglers have speculated that trout find the ant’s distinctive formic acid taste addictive. According to legend, Edward Hewitt, intrigued by trout’s obvious fondness for ants, popped a few into his mouth and chewed them to see if he could understand their appeal. He made a face and declared that ants tasted bitter.
In fact, Hewitt’s discovery happened accidentally when a couple of winged ants flew into his mouth, and he never claimed it was their taste that explained why trout were so attracted to them.
Most likely it’s the ant’s distinctive pinch-waisted appearance that becomes imprinted on the trout brain. Trout learn early that ants are a staple, a food source they can absolutely depend on for nourishment. The ant’s shape makes it an easily recognized target on the water.
Despite their ubiquity and trout’s fondness for ants, many fly fishermen seem reluctant to use ant patterns. Even the most experienced anglers of my acquaintance, who know how much trout love ants, generally tie one on only as a last resort.
It’s not hard to understand. Dry-fly fishing at its best is a visual experience. We like to be able watch our fly drift toward a rising fish. We hold our breath as the distance between floating fly and rising trout narrows. The sight of a trout snout lifting out of the water to intercept a dry fly is what keeps us coming back.
A properly imitative ant pattern, on the other hand, floats low in the surface film where it offers the angler no visible silhouette. It’s drab and tiny and hard to see on the water.
And fishing an ant properly seems technical and fussy. Especially in low-water mid-summer conditions when they are most effective, ants require long (12- to 15-foot) leaders and fine tippets (6X or even 7X). They must be presented with an absolutely drag-free drift, and even then, energy-conscious trout will rarely move more than a few inches from their feeding station to eat the tiny morsel. Trout seem to know that there will be plenty more ants coming their way.
When I’ve located a feeding trout in smooth shallow water, I compensate for the visibility problem by sneaking up behind it. I approach from directly downstream. I wear drab clothing, wade cautiously, keep a low profile, and as I approach the fish’s position, I don’t hesitate to kneel-walk on the streambed. If I move slowly and carefully, I can often creep to within 15 or 20 feet of my target trout. From that distance, with good polarized glasses I can usually see my leader tippet and the fish himself—and sometimes, on smooth water, even the speck of a size-20 ant. I try to make short accurate casts, and I watch how the fish reacts to my fly.
In broken water, I don’t even try to follow the drift of my ant imitation. Instead, when I see a trout rise in the vicinity of where I think my fly is, I gently but firmly lift my rod, on the theory that nothing ventured is nothing gained—or, as my friend Bill Rohrbacher says, “No guts, no glory.” More often than not, I come up empty, and sometimes pulling the fly and leader off the water spooks the fish. It’s a reasonable risk for the reward that comes with the thrumming surge of a surprised trout at the end of my line.
The visibility problem can also be solved with a strike indicator. Cut a little piece of foam stick-on indicator (the smaller the better, since the air resistance of full-sized commercial indicators inhibits smooth accurate casting with small flies and fine tippets) and pinch it onto the tippet knot, about 3 feet from your fly. Don’t watch the indicator or wait to see it twitch before you set the hook—that’s usually too late. Simply use the indicator to help judge where your fly is on the water, and raise your rod whenever you see a fish rise in that area.
A standard dry fly also works well as an ant locator. Tie a size-16 or size-18 Wulff or Elk Hair Caddis to your tippet, knot 3 feet of 6X tippet to the bend or the eye of that fly, then tie an ant pattern to the end of the 6X. The odd trout that rises to the dry fly itself is a bonus.
About fourteen thousand species of ants crawl on the earth’s surface. They come in a bewildering variety of colors—black and cinnamon are the most common, but I’ve seen dark brown, bright red, pale yellow, and even bi-colored ants floating on trout streams. They range from 1/16” to more than an inch in size. As many as a dozen different species can be present on the water at any one time. So even when you’ve figured out that trout are eating ants, matching the “hatch” can seem impossible.
Fortunately for the fisherman, while trout often feed on ants in preference to the
other insects available to them, they rarely select one specific species of ant to the exclusion of the others. Sometimes they may favor black over red, and sometimes size makes a difference. But usually I’ve found them opportunistic. When trout want ants—as they generally do—almost any size and color imitation will take them, provided it offers that distinctive wasp-waisted profile.
When a swarm of flying ants falls on a stream, on the other hand, trout can be as infuriatingly selective to size and color as they are to mayflies. Trout feed voraciously on flying ants. But usually the fisherman must match the hatch, or he’ll catch no fish.
Luckily, flying-ant falls are predictable. They typically occur in late summer on warm, humid, windless afternoons. The well-prepared angler learns from experience what to expect and comes prepared with a selection of flying-ant patterns customized for his waters.
Both winged and wingless ants are terrestrial insects. Their appearance on the water, while common, is always accidental. They cannot swim, so they drift helplessly, borne afloat by surface tension, before they sink and drown. In riffled water, where they sink rapidly, subsurface ant imitations are especially effective. Fish them without weight just a few inches deep to imitate the real things.
Floating ant imitations can be made from a variety of materials— cork, deer hair, closed-cell foam, and dubbing, with a couple turns of clipped or bunched hackle for legs. All are effective provided they are designed to drift flush in the surface film rather on top of it. Add a pair of laid-back hackle tips and you’ve got a flying ant. To make sinking ants, simply form lacquered balls of tying thread for the bodies. The key to imitating ants is reproducing their large oval abdomens, narrow waists, tiny legs, and round heads.
Ants are notorious for ruining picnics. But when they’re on the water, as they usually are, they provide a buffet for trout—and a trout-fishing banquet fit for an angling king.
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