On the Fly: It’s just a phase

Scott Spooner
On the Fly
A brown trout caught on the Roaring Fork River.

Are you getting your fly boxes ready for another spring and summer? Winter midge fishing will soon be in our rearview, and having all of the usual spring and summer insects stocked up is important. Even more so is having the proper fly for each stage of that insect’s life cycle. Most of our native aquatic insects spend the majority of their life in the water and only a day or two as a winged adult, so we need to cover the nymph, emerger, dun and spinner phases of most mayflies.

Mayflies here in the Roaring Fork Valley consist of March browns, blue wing olives, pale morning duns and green drakes, with a smattering of blue quills, seratella and plenty of others that aren’t even on our radar. Mayflies spend the majority of their life subsurface, and then emerge when conditions are right. Most emerger patterns incorporate a bit of flash to mimic the tiny air bubbles they utilize to get to the surface of the river.

After the adult dun phase, female mayflies go into their spinner phase, which is another metamorphosis outside of the water. The spinners are the egg-layers and are recognizable from the dipping dance they do over the water’s surface, ovipositing future generations. When it comes to mayfly imitations, we need to carry nymphs, emergers, duns and spinners to be effective.

Caddis are prolific here, especially on the freestone Roaring Fork, Crystal and Colorado rivers. We see case-building caddis, free swimmers and giant sedges in this valley. Most caddis larva (nymphs) are lime green in color and the adults vary from cream colors to black. Caddis emergers (pupa) fished on the swing under a dry fly are deadly around here. Caddis mate in swarms, females oviposit in the evenings, and they do not have a spinner phase like the mayflies.

The more we get out there and fish, the more we begin to understand these life-cycle phases and comprehend how important it is to not only match the hatch, but match the life-cycle stage of the hatch, too. Mimicking size, shape and color are key. No matter who you are, there is a lesson to be learned every time you head to the river. You just might have one of those eureka moments this year!

This column is provided by Taylor Creek Fly Shops in Aspen and Basalt. Taylor Creek can be reached at 970-927-4374.


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