Fly Fisherman Throwback: A Primer of Stream Entomology–VI

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, Dave Whitlock, 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 February-March 1973 issue of Fly Fisherman magazine. Click here for a PDF of the print version of "A Primer of Stream Entomology-VI."

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Part Six of a series of articles designed to familiarize fly fisherman with the practical aspects of stream­ side entomology. The series will cover the favorite fare of trout, smallmouth bass and even bluegill in all of their habitats, slow water and fast, from farm ponds to high mountain lakes. Mr. La Fontaine is both a scientist and fly fisherman who goes where the fish and the hatches are.

The lure of the mountains hooded with summer snows, of the lakes crimped down into steep valleys, of the trout gathered in crystal waters, weighs heavily on a man as he waits for summer adventure. He plans his fly fishing trips with maps, and camping gear, and hiking boots, because this type of fly fisherman works as much to reach his water as he does to catch fish. He's willing to search and work to find his Shangri-la, but he knows that, if the lake is healthy and the fish of fattened size (not including lakes where the trout are skinny and stunted and too hungry not to grab any fly), his fish will have definite preferences and habits, and to catch the best fish in a lake he will have to angle skillfully and knowledgeably to meet the whims of the fish.

The fish of the high mountain lakes, being practical creatures by necessity, usually tailor any such whims to the actions of the insect feed of their environment. The fish gather at points in a lake where a selected feed is concentrated, and a nearby spot of water may be nearly barren of fish because it is nearly barren of vulnerable insect prey.

There were two days in late May one year that I spent with Dick Fryhover at Heart Lake. We were trying to time the spring feeding spree of the grayling that were abundant in the lake, but we were too early and met the remnants of a blustery winter instead. The first day was not too bad, cloudy but not raining, and our group spread along the reef to cast flies to cruising fish. We all caught fish, and the rise of fish was consistent as mayflies came off the water. I called over to Dick and his son that things were "not too bad."

Young Dick, near my age and an excellent fly fisherman, waded out of the chilly water and disagreed. "No, we're here too early this year. Last year was right, when there was a heavy hatch, and in this spot I caught one hundred grayling in a little more than four hours."

I thought about one hundred grayling in a day. "Maybe tomorrow," I said.

Tomorrow made yesterday a fond remembrance, and the snow splatted in large, wet flakes. We waited on the shore until 1:30pm, the water surface barren of rises, and decided to try fishing anyway. We waded out and cast, and in fifteen minutes no one caught a grayling.

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I stood in the waist-deep water, be­ginning to shiver. The previous day a steady hand-twist gathering of line caught fish, but today it did not excite the grayling. I stopped retrieving my nymph, and watched my ungreased line slide down into a steeper angle. It sank very slowly, for a long gap of seconds, towards the slant of the deeper water. With the nymph still sinking, the line twitched and I set the hook. I played the grayling. "They're taking at bottom," I shouted.

I caught fish with the technique of "cast and wait," and always on the un­ moved sinking fly. Dick, Sr., watched me carefully until he copied the style, and he began to catch fish. I caught grayling quickly for a half an hour, all of the fish from 12 to 13 inches. I left the water too chilled to continue ang­ling, and joined the group huddled on shore.

Dick, Sr., came over to stand with me in front of the fire. He nudged me and began ribbing, as is his wont, "Go ahead and take him fishing, and he has to make the old man look bad."

I only grinned, because neither I nor anyone else out-fishes the "old man" very often, and especially not on the high lakes that he fishes and knows so well. On a day when the lake was fickle and the angling was not easy, it was a habit of the mayfly nymph that he had first pointed out to me that helped find our grayling.

I remembered one of my early fly-fishing experiences, on a trip when I went with Dick to Park Lake near Helena, Montana. We arrived and the water was covered with the rings of rising fish. I started to tie on a dry fly, but Dick suggested a nymph pattern. "Aren't the fish taking on top?" I asked.

"Some of them are, but for every fish that you see breaking, there are three feeding on nymphs below the surface."

I waded out along the shore, peering down into the clear water. I saw a mayfly nymph scuttle free of the floor litter and swim vigorously toward the surface. The insect hovered midway, then returned to the bottom. Other nymphs performed the same restless dance, with some of them rising higher or lower in the water. Occasionally a nymph, ready to emerge, swam all the way to the surface to break the outer skin, but always in the water there were many more nymphs rising and falling without bursting free into the dun stage.

At Heart Lake, on the second day as I pondered, observed, and experimented, I remembered the vulnerability of the mayfly nymph in the still water. The day before, over the skinny jut of shoal, the emergence of duns was not heavy, but we all caught fish on our artificial flies worked just below the surface because many more mayfly nymphs were moving in the mid and upper layers of water.

The difference between the two days of the trip was the harsher weather of the second day. The weather did not make any difference to the grayling, which fed actively on both days, but on the second day the weather retarded the hatch of mayflies. Not only did few duns emerge, but not many nymphs made the trial rises in the water. With the upper layers of the lake barren of the nymphs, we were angling in fishless water. Only when the sinking lure neared the weed tips did the grubbing grayling notice our flies.

I fish many lakes during mayfly hatches, and generally I find a nymph to be more effective than a dry fly when the fish seek the active food. Because a rising nymph is so vulnerable to predation in the still water, the nymph remains prime throughout a hatch, and this is unlike flowing stream water where an insect perched on a moving table is brought to a fish.

Last summer at Big Salmon Lake I watched as Dick started another group of young people fly fishing, as he demonstrated his technique of fishing the lake nymph to Peter, Jared, and Chris Habein. I recalled the text of words as I heard Dick say, "No, I think that a nymph will do better."

A heavy hatch of mayflies of the genus Callibaetis, a common mountain lake ephemeroptera, were emerging on the flat of the outflow of the lake. Dick scooped a moving nymph from the water, and held his fly near the nymph to show the resemblance. "Do you see the fish cruising?" Dick asked the shoreline clatch of listeners.

Dick cast ahead of the fish, and he let the fly sink. He began his method of manipulation, bunching line in a slow hand-twist retrieve (the retrieve popularized by Ray Bergman), and after every third grab of line he raised the rod tip slowly to break the nymph on the surface. The broad silver flash of the cutthroat was visible as the fish took the fly, jumping as the hook was set in the shallow water. Dick landed the 16-inch cutthroat, and the young anglers began their stalk of cruising fish.

The fish of the high mountain lakes, although tucked into the remote mountains of the Western states and supposedly uneducated to the abundance of anglers, follow patterns as they seek comfort, shelter, and food. They are not always easy to catch, because they are wild fish with sharpened instincts of survival. They gather with the available feed of the lake, and that is where the angler will find them.