The female stonefly deposits her eggs in the water.
The eggs drop to the stream bottom where later the nymph hatches out and lives on the bottom for one to three years.
When mature, the nymph crawls out on a stone, log or the shore where it emerges into an adult fly.
Adult flies scramble around in streamside vegetation, mate there, and fly back to the water, where the females deposit their eggs.
(Rod and Debbie Bond illustration)
June 07, 2022
By Dave Hughes
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This article originally appeared in the September 1987 issue of Fly Fisherman magazine. Click here for a PDF of the print version of "Stonefly Hatches Simplified."
It was February, a weak noon sun barely warmed the sage and dry grasses along Oregon's famous Deschutes River. Rick Hafele, co-author of Western Hatches , waded a few feet out, then turned upstream and began casting his dry fly tight up under waterside willows.
After a few casts there was a gentle swirl under his fly. Rick raised the rod to set the hook, and a 23-inch brown trout tumbled out into the main force of the river and ran Rick 200 yards downstream before he finally coaxed it into his net.
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"What are you using?" I asked Rick as he slipped the fish back into the cold water.
"A Little Brown Stonefly pattern. Haven't you seen them flying around?"
"A few," I answered, "but I didn't think the fish were keying on them."
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"They're taking the stones because they're the only insects around this early in the season."
I looked at Rick's dressing. It was a simple size #14 fly with a brown dubbed body, flat woodchuck-hair wing, and grizzly hackle collar. That's all there was to it. It looked too simple to work during something as complicated as a stonefly hatch, But he cast it again and caught an other brown. Finally he gave me one, and I started catching trout, too.
Stonefly Life Cycle The stonefly lifecycle is an interesting circle. The female fly deposits her eggs in the water; the nymph hatches out and lives on the bottom for one to three years. When mature the nymph crawls out on a stone or the shore where it emerges into an adult fly. Adult flies scramble around in streamside vegetation, mate there, and fly back to the water to deposit their eggs, completing the circle, Most dry-fly fishing over stonefly adults comes during egg-depositing flights rather than actual hatches.
Matching the Natural At first glance, stoneflies seem to be infinitely varied. There are Little Browns, Little Greens, Yellow Sallies, Golden Stones, salmon flies, and many others. But out of all this confusion something simple arises: Stoneflies, no matter how varied their size and color, all have the same shape.
Stoneflies, no matter how varied their size and color, all have the same shape. (Jim Schollmeyer photo) The key characteristics of adult stoneflies are two tails which are sometimes minute, long antennae, and four wings of equal length, always held flat over the back of the abdomen when the insect is at rest. This shape is the same for all of them: They all have long abdomens which are usually slightly flattened top and bottom, muscular thoracic segments with six legs attached, and wide heads with eyes out to the sides. Those flat wings, held back over the body, are the key to identification, and also the key to imitation.
The three parts of the stonefly you want to imitate are the body, the wings and the legs. It is simple to choose a pattern style, then to vary the size and color of it to match all the various stonefly species. You don't need to know a lot of entomology, or any Latin names.
The fly Rick ties to match the Little Brown Stone is a variation of the Sofa Pillow, originated by Pat Barnes of Montana to imitate the larger Golden Stone. The Sofa Pillow has a red-dyed mallard-quill tail, a red floss body, fox-squirrel-tail wing, and thick brown hackle collar. It's an excellent combination for floatation–the thick hackle and silhouette–with the red body and squirrel wing laid flat over the back. The Sofa Pillow style can be varied to match all other stoneflies.
The most common sizes and colors of stoneflies all across the country are the Little Greens (#14 and #16), the Little Browns (#12 and #14), the Little Yellows or Yellow Sallies (#10 and #12), the Golden Stones (#6 and #8), and the famous salmon fly (#4 and #6). All of the imitations should be tied on long-shank hooks (Mustad 9672) because of the long body and wings of the naturals.
Bodies should be of fur dubbing or floss, and should be based on the under color of the insect. Natural stoneflies are often a lighter color on the belly than on the back. It's the underside trout see, and that's what you must imitate.
The flat wings are represented with woodchuck guard fibers in the smaller sizes, squirrel tail in the mid-ranges, and with high-floating elk hair for the largest imitations.
Choose the hackle based on the leg color of the naturals. If you have any doubt, use a mixture of two colors. Brown and ginger works well for the golden and yellow stones. Grizzly, a smoky mix of black and white, is a good choice for any of the browns and olives.
Presentation for all of the stonefly dressings should be upstream, fished with a dead-drift float. If that fails, however, try giving the fly a bit of action. Hop it an inch or two, or even skitter it boldly across the surface. Stoneflies, when depositing their eggs, can show trout quite a bit of movement, and selective fish sometimes key on the movement of the natural rather than its size and color and shape.
By doing a little collecting of your own, out on the stream, and by choosing a variation of the Sofa Pillow style fly to match what you collect, you will be bet ter prepared to take trout during a stonefly flight than you would be if you tried to carry a box filled with every stonefly dressing in the book.
Improved Sofa Pillow Fly Recipe (Dave Hughes photo) HOOK: Mustad 9672, #4-#10.THREAD: Brown.TAIL: Dyed orange elk hair tied short.RIBBING: Brown hackle tied in by tip and palmered along body.BODY: Orange synthetic dubbing. WING: Woodchuck tail hair extended to end of tail.HACKLE: Brown, tied heavy.NOTE: Color of dubbing, wing and hackle can be changed to suit local hatches.
Dave Hughes lives in Astoria, Ore.
This article originally appeared in the September 1987 issue of Fly Fisherman.