St. Vrain Angler

Fly Of The Month

May, 2004: our fly of the month is the Golden Stonefly. This is the time of year when the bugs get active, and when they do so hungry, greedy trout eat them. Golden stones are relatively shy bugs. I say this because they do not hatch in profusion like midges or some mayflies and caddis do. Rather, golden stones come off in little spurts, and keep coming off during the course of the summer.

Stoneflies need lots of oxygen to survive. Their systems are not particularly good at assimilating oxygen, so they live in spots where they can get lots of oxygen, which means they live near fast moving water. In riffles and runs, and on the bottom of large rocks stoneflies roam around hunting for food. They prey on other smaller insects, eating neighborhood bugs. The gills of a stonefly are found under the thorax, rather than along the abdomen like mayflies. All stoneflies have two tails and three distinct wing pads. They look prehistoric!

Note the length and breadth of the legs on this nymph! These guys hold on really good, and have to because they are terrible swimmers. When they get cut loose from their grasp, they flail about, trying to find a foot hold to grasp. Trout know this, too, and watch for the bugs as they wash away.

All insects go through instars. This occurs when the bugs grow. All insects have an exoskeleton. When they need to grow, the skeleton does not, so they shed it - like a snake shedding its skin - and grow a new one. When this occurs, the bugs turn a creamy-white color and are much more vulnerable to being washed away and eaten. Once in a while, it is a good idea to fish a cream colored stonefly nymph. If you tie your own, make the bug look like the picture above, but tie it in a light color. You'll see.

The nymph at the left shows the light color on the bottom of a stonefly nymph. Note that the top is dark, and the bottom light. They hide really well. Again, note the dominant size of the legs in proportion to the rest of the bug.

The larger golden stones hatch from eggs, then live in the water for three years before emerging. During this time they eat, grow and cause havoc with the neighborhood. Stoneflies migrate with water levels, and also undergo behavioral drift. This occurs when bugs overpopulate an area. To escape the stonefly apartment complexes, numbers of bugs let go of their lease and drift along with the current until they find new lodgings. Along the way, some are summarily eaten by opportunistic trout.

Stoneflies emerge along the edges of streams. They migrate from the streambed to the edges, and then climb out of the water onto a rock, larger log or other obstacle on which they can attach themselves. When they find the right spot to attach, their shuck begins to dry and then splits. The adult insect climbs out of and leaves the shuck behind (at left) in order to dry its wings before flying off to mate. Often, after leaving the shuck, the adult insects fall into the water and float along trying to find something to grasp in order to escape the water, which has been their home for upwards of three years.

The adult golden, shown at left, is lovely. When they fly, they look like small pterodactyls coming right at you! In my case, they often come in for a landing on my beard. The first time I saw these bugs emerging I didn't know what to think! Now, I look for them with glee, knowing that if I see one, the fish are seeing them too.

Trout are opportunistic feeders. At least that's the way I choose to think about them. When the stones are around, I always think there is a nice trout holding right along the bank, waiting for a clumsy bug to emerge and then fall off into the water for lunch. Little does the bug know that it is both invited to and will be lunch! With this in mind, I'll often fish along the banks, watching for slightly deeper pockets or places where the riverbed has been cut out by faster flows. That's where a fish will be holding, often in or around very shallow water in fact. One or two good drifts will usually do the trick. If the fish is there and wants to eat an adult, it will take the fly as long as the drift is good. They are a big bite of food, after all.

Fly imitations will include nymph and adult patterns. For our area, a 20" with or without a bead is a good nymph. A large, two-wired Copper John with olive and yellow wire will work well, as will a prince nymph. Be creative with your fly tying. The bugs are relatively flat, wide and juicy. Keep the juicy part in mind when tying these bugs - add a little jelly, if you like. Okay, maybe not. Tying stonefly nymphs with golden, olive, yellow or brown furry foam and a dark turkey wing pad is an excellent idea. Use hen material for legs.

Another excellent nymph pattern is tied "in-the-round." For this pattern, use biots for the tail, furry foam, peacock or dubbing for the abdomen with a turkey quill shell back ribbed with copper wire. For the thorax, dub, use peacock or furry foam - or whatever other material you like; be creative folks - and palmer grizzly and brown hackle through the abdomen. No wing case.

One of the finest and most useful adult stonefly imitation is a Stimulator. Tie them in various sizes and colors to meet and match what you think you see. I think it is about the size and silhouette the fly makes on the water.

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