The Elusive Pteronarcys Hatch :: Cutthroat Anglers

Is it on? Are the salmonflies on the reeds? What’s the water, temp? Are flows too high for fishing? When is the best time for the hatch to start? What size are they? What week/month of the year does it start? Where can I find them on the river? What section of river do they start? Do they make it into the canyon? Do they make it through the canyon? What color are they? What’s the best pattern to imitate the nymphs? The adults? How many days does it last? Do they bite? Do they sting? How do they taste?

All very good questions and we’ve heard them all (except for maybe “How do they taste?” but the answer is delicious in case you were wondering). The truth is, the largest species of stonefly in America is pretty elusive. With all of the different factors that come into play for locking down when and where these prehistoric insects emerge from the depths is pretty challenging and ever-changing. The golden rule for us here at Cutthroat is 52-54 degree water temps for 4-5 days in a row. You can see how this might be difficult to pin down, especially during runoff where you have constant changing water and weather temps. When it gets warm out, the water cools down due to snowmelt. When air temps cool down, snowmelt stalls and the water temps slowly increases due to some of those small, shallow feeder streams warming up during the day. It is confusing; I know… we can come back to this (maybe).


The life cycle of the Pteronarcys, pronounced SAM-ON FLY (or tear-a-nar-sis) is pretty basic: egg, nymph, adult. Post mating, the female salmonfly cruises low to the water to drop her egg sac. The egg sac then anchors on the bottom of the riverbed where the bugs will grow and develop for about 3 years. After their 3 year “incubation” period, and the water temps cooperate, the nymphs begin to gather in clusters under rocks near the bank. From here, they begin to emerge out of the water and up onto the bank, usually at night. Their goal is to get to rocks or riparian vegetation to molt their nymph shell and emerge as the giant, glorious, clumsy beasts that we’ve all grown to know and love.



So there is a brief rundown on the life cycle and very loose rules for the hatching salmonfly. Quick recap; egg, nymph (fishfood), 3 years, warm water, crawl to bank (fishfood), crawl out of water, hatch, dry/mate, clumsily fire around running into any and everything that gets in its way (fish food/human food). How does this relate to fly fishing and one of the most renowned hatches in the west, you might be asking?  Simple, the amount of food in the water would turn any predator into a gorging beast. The nymphs can get up to almost three inches in length, and that’s a pretty good meal for a hungry trout. The adults are so big and clumsy that the slightest breeze or knick of a branch and they are in the water, wet, and barely able to move. This is a pretty easy target for any kind of fish looking up.         


As far as imitations go, you have a wide variety of options for salmonfly patterns. One of the most famous subsurface patterns for the hatch is known as the bitch creek (1). It has an orange and black body, brown hackle, white antennae and tail: pretty simple, but very effective. As far as a newer style patterns, our go to in the shop is the Pats Rubber Leg in black (2), black/brown (3), or orange/brown (4). Check our Youtube or Facebook page for that fly tying tutorial. A few other usable sub surface patterns are the super stone (5), shagadelic (6), or the brown wired stone (7). Then we get to the good stuff, the top water flies! My personal favorite pattern for top water salmonfly is the orange body Chernobyl ant (not pictured, it’s a secret…). We have a wide variety here in the shop, and to each his own, as far as most effective. Some of the heavy hitters from last year included the in-the-zone stone (8), the fuzzy wuzzy orange (9), the chubby Norman (10), the Rogue foam stone (11), or the plain old chubby Chernobyl (12). There are so many options and the hatches can be so thick, that sometimes you can just throw orange things out there and have success (sometimes).



So there you have it, that’s most of what I know about salmonflies, and most of what you need to know to be successful out there. Remember that this hatch and these bugs are elusive and it is very hard to pin down the actual hatch time. That being said, if you can get it right, you can have some of the best days of your fishing season out there. Swing through the shop and pick up some new bugs, keep an eye on flows and water temps, and go get after it!


P.S. don’t forget to eat one to appease the salmonfly gods!

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