Fly Fisherman Throwback: Ants, and the Two Distinct Ways Trout Feed on Them

Now praise we the lowly ant–a food form that trout seem to relish, but that is often too casually dismissed by anglers.

August 07, 2023 By Ernest Schwiebert

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, John Voelker, Al Caucci & Bob Nastasi, 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 June 1978 issue of Fly Fisherman magazine. Click here for a PDF of the print version of "Ants."

The iron bridge shuddered when it took the weight of the car, and a fine dust of gravel rattled through its board flooring into the river. The hot wind riffled upstream under the bridge, smelling of the hay meadows and ripening grainfields in the Susquehanna Country. Locusts buzzed in the trees across the river, where the gravel road wound into the open valley beyond.

"Penn's Creek," I thought.

The current was surprisingly strong and milky below the trusswork bridge. There were·no rises anywhere and it seemed lifeless. The country road crossed the corn fields toward a simple clapboard farmhouse. Its screen porch stood deep in the shadows of a sheltering elm. The clatter of mowing machines drifted on the hot wind, and dairy cattle watched from the pasture.

Wetzel, read the galvanized mailbox.

The old man rose from his fly-tying table on the porch and opened the screen door. "Charles Wetzel," he introduced himself. "We've been expecting you all morning." We shook hands warmly.

"What's hatching?" I asked.

"Nothing!" he laughed. "It's too hot for fly hatches!"

"Fishing been pretty slow?" I said.

Wetzel finished a big lacquer-bodied ant, touching its black silk thorax and gaster with clear lacquer on his bodkin, and lightly hooked it into the porch sill to dry.

"Fishing's been pretty good," he said.

The old man nodded and grinned knowingly. Charles Wetzel was one of the living legends among American trout fishermen. Books like Practical Fly Fishing established his reputation as a stream tactician and expert on Pennsylvania fly hatches 30 years ago. At the time of this visit, Wetzel had retired 15 years earlier to fish the Pennsylvania rivers of his boyhood and had long been the dean emeritus of the Weikert stretch near his Penn's Creek farm in the Appalachians. Wetzel taught me a lesson that afternoon. It was still hot and windy as we locked the car and walked down through the woods to Spinning Wheel Pool. We started fishing below a tiny feeder that mingled its cold flow with the river. The smooth-flowing run held the cold tributary water tight against the rocky, tree-sheltered bank. The run lasted 200 feet.

There were still no hatches. "Think I'll fish a big variant," I said. "It produced on the·Loyalsock last night."

Wetzel smiled and selected a big ant imitation.

No fish were rising anywhere. The heavy current surged around our waders, milky and rich with limestone springs. Wetzel worked the spring run under the trees, while I tried the big variant upstream. There was no action except for a small fly-sliming bass, but Wetzel was picking up trout with disturbing regularity.

Finally I swallowed my pride and waded out to his position in the current. Wetzel placed another cast into the cold currents in the shadows against the bank. His pale English fly line, patiently dressed each morning with Mucilin on the farmhouse porch, drifted on the current and paused gently as a fish stopped its swing. The old man raised his rod as a fat 16-inch brown fought angrily under the trees.

"They sure want ants!" I said admiringly.

It was a fine lesson about trout fishing in hot weather. Few anglers realize that ants are a major factor in the trout diet, since most fly fishermen are more conscious of mayflies and other aquatic insects. All fishermen have seen trout taking ants during the hot afternoons of spring and summer, most without realizing what the fish were doing as they sipped and bulged softly in the surface film.

Ants are terrestrial rather than aquatic insects, belonging to the order Hymenoptera and the family Formicidae. There are literally thousands of individual American species. Since they are the most numerous of insect forms, a complete dictionary of flies dressed to imitate them is impossible. However, it is possible to select prototypical colors and sizes that will provide patterns imitating a huge number of species.

Ants are extremely interesting, with complex social orders consisting of males, sexual females and semifertile females called workers. These workers seldom reproduce. Worker ants can vary in size, and some become soldiers. It is these worker ants that are most commonly seen and are therefore a major factor in the trout diet. Since these asexual forms are wingless, most fishermen believe all ants are wingless.

However, the sexual forms that mate annually are fully winged and engage in nuptial swarms. Once these mating flights are over, the males die and the females cast their wings before starting to rear their young. This baby-sitting function is sometimes assumed by slave species in some ant families. Other insect species that occasionally live with ant populations are such genera as Atemeles beetle larvae and adults, Amphotis and Dinarda beetles, and ant-mimic beetles of unusual genera such as Crematoxenus and Mimanomma and Mimeciton.

Ants are familiar to everyone. Yet few anglers have studied their structural morphology. Their functional components are the head, thorax-like structure called the pedicel, the legs, antennae and funicular joints, and the fat abdomen called the gaster. Our representative American species for a complete set of fly-dressing prototypes can vary from the minute Monomorium erga togyna at approximately one-sixteenth inch to the huge Western carpenter ants classified Camponotus occidentalis, which measure as much as a full inch. The angler fully prepared to match ant forms on most American rivers must have 40-odd patterns in his bag of tricks.

Most fishermen have seen flying mating swarms, so it seems no surprise that winged ants are included in several books on the literature of angling. Scotcher included ants in his Flyfisher's Legacy in 1800. Carroll covers various Formicidae of the Scottish lowlands in his Angler's Vade-Mecum 18 years later, and Bainbridge published his Fly-Fisher's Guide at about the same time. Alfred Ronalds published his classic FlyFisher's Entomology in 1834, with exquisite watercolors of the British red ant. Halford included watercolors of the same winged Myrmica rubra in his books in the latter years of the nineteenth century. Similar watercolors of mating ants are found in American Trout Stream Insects and the first major American book on trout-stream entomology, the little Book of Trout Flies published by Preston Jennings in 1935. However, each of these writers was preoccupied with winged ants in mating swarms.

A pencil drawing of two ants - one winged and one wingless. — (Robert Seaman illustration)

Since fish rising to mating swarms of ants are obvious in their cause-and-effect relationships, it should be no surprise that most fishing authors wrote about such incidents. My first experience with flying ants came during early boyhood on Loomis Lake in northern Indiana, when the bass and bluegills refused the usual hair frogs and popping bugs to cruise the surface, inhaling the exhausted ants by the thousands.

Some years later on the Gunnison in Colorado, our party encountered a blizzard-like mating swarm of ants. The big rainbows went wild, and we went fishless with our usual flies. There were occasional pale Stenonema hatches, but the trout ignored these fluttering mayflies to gorge themselves on ants. Their heresy drove me indoors to the fly vise.

"They haven't read Halford!" laughed my friend Frank Klune. "They don't know they're supposed to prefer mayflies."

Some fish were taken on our hastily dressed ants, but on the whole our attempts were relatively unsuccessful. We tried bodies of orange silk shaped into antlike images and soaked in lacquer. This achieved a shiny head and gaster but made bodies better suited to wet flies than the spent ants floating awash on the surface film. It never occurred to us that dubbed fur bodies would achieve a similar antlike sheen when wet and would float as high as the naturals.

But these were experiences with flying ants, and it would be another ten years before my fishing with Wetzel–and later with those wizards of Letort Spring Run, Charles Fox and Vincent Marinaro–taught me the almost daily role played by the wingless worker ants in the trout diet.

Curious anglers need not study ants in the manner of the cantankerous Edward Ringwood Hewitt, author of Telling on the Trout and A Trout and Salmon Fisherman for Seventy-five Years, who actually ate ants to discover why the fish liked them. Hewitt concluded that it was the tartness of their formic acid content that appealed to the trout, much like people preferring dry wines or dill pickles or olives. Of course, we cannot know how ants taste to trout, in spite of Hewitt's report on their sharp taste to the human palate. Still the reason why trout take ants is relatively unimportant, since it may only result from their abundance and mere availability, and trout do take them readily on rivers everywhere.

Since Hewitt performed his taste test a half-century ago, the steady erosion of trout habitat in America has made terrestrial insects such as ants more important in the trout-stream scheme of things. Lumbering and its slow thermal pollution, human and industrial wastes, soil erosion and the leaching of fertilizers into the rivers, detergents and phosphates, and the careless stripping of stream bed gravel–plus the effects of pesticides and herbicides on our ecosystems–have all had their grinding impact on the familiar aquatic fly hatches. Terrestrial insects like ants are a hardier breed, and as the better-known aquatic insects diminish, the fish have begun to change their feeding habits. Ants are an increasingly important part of their diet equation. The physical configuration of both winged and wingless ants has considerable effect on the way ants are exposed to trout in various types of water. Like all terrestrial insects, ants are most active in warm weather and are most often found in trout stomachs during hot, windy days. Their morphology has an effect on dressing imitations, since ants neither float nor sink well. Ants on quiet currents have a ratio between weight and leg-body displacement that means they float barely awash and almost pinioned in the surface film. Most trout-stream insects either drown or float on the current like mayflies. They trigger simple wet-fly fishing or are easily visible on the surface, disappearing in the eager rises of the trout. The fact that wingless ants are not seen swarming, and those that fall into its currents are drifting in the film are hard for fishermen to see, make them difficult to discover as well as imitate.

Two distinct types of ant feeding occur. Fish in quiet pools and flats will dimple and bulge softly to Formicidae trapped in the surface film. Trout in pocket water and broken rips pick up mostly drowned ants.

Both types of riseforms have the sipping rise or gentle underwater swirl of a fish capturing helpless insects that cannot escape.

These characteristics of ant feeding result in three types of imitations. Wet patterns are dressed with dubbed crewel wool bodies and soft hackles using heavier wet-fly hooks. These wet versions are usually limited to the sizes larger than 16 in my fly books. Dry-fly ant imitations are dubbed with fur and dressed on extrafine hooks, adding pale dun and hackle-point wings to simulate individuals from a mating swarm.

Since those many classroom afternoons on difficult limestone streams such as Big Spring and Falling Spring Run and the Letort, and equally demanding Spring Creeks in Idaho, Wyoming and Montana, I have found ant feeding on many rivers of three continents. During my experience on American rivers from California to Maine, I have evolved a series of 40 ant patterns that have served me well in the last 20 seasons. [This series of patterns is described at the end of this article. THE EDITORS.]

The big western carpenter ants were responsible for the largest trout I have taken in the United States. It was caught on a size 10 Giant Carpenter Ant in a marshy spring creek at Jackson Hole. Bob Carmichael had warned me several times about the big rainbow the summer before, but I did not locate it that season.

"It's a big cockfish," Carmichael warned. "Used to weigh about twelve pounds, but he's past his prime and ugly as sin!"

"I'll be careful," I laughed. "Might charge when he's wounded!"

"Lives under a deadfall," Carmichael said, ignoring the joke.

Jim Rikhoff was driving down from the Yellowstone to fish the spring creek marshes with me one evening in June a season or so later. I had been making a television film on the Falls Pool above Jenny Lake that summer, and when the day's shooting was finished, it was a relief to get away from the special-effects men and camera crews and really go fishing. Rikhoff had called me in Jackson at breakfast, and we had agreed to meet on the stream later that evening.

Rikhoff was late and I hiked down alone in the swampy meadows to the stream. It was still and unusually warm, and a huge mating swarm of big carpenter ants hovered over the smooth, pondlike currents. Several cutthroats cruised together, picking up fallen ants in the surface film, and I started to stalk them.

Crawling on hands and knees in the coarse grass, I watched the school of cutthroats work down from a riffle toward a rotting Engelmann spruce that lay almost entirely across the stream. The smooth current eddied and sucked at its dead branches, sweeping past its free end in a slick current tongue against the grass. The flow had cleared the silt from the gravel below the tree, and a pair of cutthroats had spawned there.

During my first evening on the pool, I had discovered the location of the big rainbow by accident. Two goodsize cutthroats were nymphing above the deadfall, but my first cast unhappily got fouled in its branches. It was the only pattern like the early hatches in my fly book, so I spooked the cutthroats intentionally and waded out to retrieve the fly. The current was chest deep, and I worked slowly out to the tree and unhooked the little nymph.

Just below the tree, staring balefully up through the tangled branches, was the mammoth rainbow. Its ugly snout was scarred, its gill covers and flanks were blood red, and its mammoth head dwarfed an emaciated body. It looked mean enough that I was startled.

"He really is ugly!" I thought.

I backpedaled stealthily and tried fishing the big rainbow an hour later, but it ignored me and stayed securely hidden in its thicket of branches, and finally I got hooked in the deadfall again. During the next few days it disappeared completely.

Rikhoff was still tardy, and I crouched in the coarse grass, waiting for the school of cutthroats to work its way back into casting range. Suddenly there was a soft rise to a struggling ant just below the deadfall, and I worked a quick cast over the fish without thinking. The big ant sank and drifted through the holding position of the trout and stopped. It felt as if the hook had caught and held on the pebble bottom.

"Work it loose carefully," I whispered

I tightened imperceptibly, hoping to free the hook without frightening the fish, when it wallowed angrily. Huge waves rolled down the current.

"My God!" I thought wildly. "I've hooked him!"

A pencil drawing of a rainbow underwater in weeds. — (Robert Seaman illustration)

It was the big rainbow, and I had not changed the two-pound tippet. The fish shook itself angrily, turning back toward the deadfall on that fragile nylon. "You've got to stop that!" I thought, charging out into the waist-deep marl between the fish and the tree.

The wild splashing worked. It was too early in the summer for weeds, and I let the rainbow circle futilely around the 60-yard slough, wearing its strength with gentle pressure. Each time it threatened to reach the tree, I shouted and threw water with my free arm. Late in the fight, it finally succeeded in tangling the leader in some beaver sticks, but it was too weak to exploit its opportunity. It lay belly-up in the shallows and I waded cautiously across the current, seating my fingers across its gill covers. I carried it ashore.

"Take him if you catch him!" Carmichael had insisted. "He's too far past his prime for spawning–take him!" Carmichael was right. The big cockfish was ugly and scarred, its distended skull too large for its atrophied body. It had not spawned that spring, and it weighed just under nine pounds.

Rikhoff arrived just after I killed it with a mercifully quick blow from my priest-knife. "It's a lie!" He laughed. "You didn't catch that monster in that little creek!"

Several hours later we celebrated at one of the refurbished Victorian saloons in Jackson. The big rainbow lay in state on the bar, and the waitress arrived with our second round of sour-mash whiskey.

Rikhoff raised his glass with a ceremonial flourish: "Now praise we the lowly ant!"

Ants For All Occasions

[The following are the author's pattern descriptions for 40 different ant patterns (yes, 40) that should enable the angler to meet most ant-fishing situations. Naturally we don't expect the angler to tie up each of these patterns for his fly box, but many of these files should be useful in imitating local varieties. THE EDITORS]