Crawling Toward the Hatch: The Salmonfly Experience and Common Stonefly Guide

I was fishing the upper stretch of the Colorado river near Kremmling Colorado in early June hoping to get into one of the most iconic hatches there is – The Salmonfly hatch. There were reports that a few of them had started coming off and I wanted to finally be there for the big day. This was my 4th year coming up to the canyon and waiting for all the elements to be right. In years past I was always a day or two early or a week late, but not this time! I watched weather reports, talked to anyone who had ever been there, took time off work and there I was waiting on the bank for what I had built up in my mind as the greatest Stonefly hatch ever. As I impatiently waited and questioned my sanity, I went through the months of research I had done on Stoneflies for the IdentaFly app.

About the Stonefly

Stoneflies spend most of their lives underwater as nymphs. Inhabiting clean, cold, oxygen-rich streams and rivers – often a sign of excellent water quality. Depending on the species and environmental conditions they may live submerged for 1-3 years before emerging as adults. During this time their appearance changes very little aside from size; they simply grow larger.
Unlike Mayflies or Caddis, Stonefly nymphs are poor swimmers. They move with an awkward, clumsy motion. Preferring to crawl along the stream bottom or cling tightly to rocks and submerged debris using their strong legs and claws. Many species are opportunistic feeders – some are herbivorous, grazing on algae and decaying plant matter, while others are predatory – hunting smaller aquatic insects or even other Stoneflies.
Because of their weak swimming ability, Stoneflies are often dislodged by fast currents, especially during spring runoff or after rain. This is when trout take advantage of an easy meal tumbling through the water column.

Pro Tip: When fishing a Stonefly nymph pattern, subtle line lifts or “micro-pulls” to imitate this clumsy drifting motion. A dead drift presentation with the occasional twitch or bump gives the fly the lifelike erratic movement of a real Stonefly struggling to regain it footing on the streambed.

I tied on a size 10 Pats Rubber Legs that I had tied the week before, dark tan with an orange band and enough wire wraps to make sure it sunk to the bottom quickly, followed by another of my favorite patterns the Bitch Creek Stone.

Stonefly Lifecycle

As stonefly nymphs near the end of their underwater life, an incredible transformation begins. When water temperatures and day length reach the right balance, their internal “clock” signals that it’s time to leave the safety of the streambed and begin their shoreline migration. This slow crawl toward the banks is one of the most important feeding opportunities of the year for trout. The nymphs, heavy-bodied and clumsy, are easily swept away by the current, creating an all-you-can-eat buffet for fish waiting in ambush along seams and shallow runs.

Each stonefly species follows its own unique rhythm—some respond to rising spring temperatures, others to the cooling of late summer evenings. Factors such as water temperature, flow rate, elevation, and the nymph’s age all determine the exact timing of their emergence. When conditions are perfect, thousands of nymphs make their way to the shallows at once, crawling up rocks, logs, or even streamside vegetation to split their exoskeletons and emerge as winged adults.

A telltale sign that this event is underway is the presence of empty stonefly shucks clinging to riverside rocks, bridge pilings, or willows. When you see those papery brown casings, you can be certain the hatch is on—and it’s time to transition from fishing subsurface nymphs to adult stonefly imitations near the edges of the river where trout are now looking up.

Experiencing the Salmonfly Hatch

My first cast—and as much as I’d love to say it connected with a fish—it was a knot. Get it? A tangle so bad I had to cut it all off, re-rig, and start over. The next couple of hours brought the occasional trout, but nothing close to what I had built up in my mind.

As the light began to fade, I caught a glimpse of movement near the bank—a few adult Salmonflies fluttering clumsily out of the bushes. How had I missed them crawling from the river to dry their wings? They’re anything but graceful, and when I looked closer, I saw their empty nymph shucks scattered by the hundreds along the rocks. My stomach sank—had I already missed the peak of the hatch?

The first few casts and drifts produced nothing, and with darkness closing in, I started thinking more about getting out of the canyon than catching fish. I’ve got this irrational fear that if I hang around too long after dark, a mountain lion’s going to make me the evening special.
As I worked my way downstream, casting and walking, I suddenly heard splashing—distinct, heavy splashes echoing off the canyon walls. I stopped, listened, and there it was again. I flicked on my headlamp, and what I saw froze me in place. Hundreds—maybe thousands—of Salmonflies were crawling up the canyon walls and fluttering in the beam of my light. The hatch had exploded, and the river had come alive.
I laid out another cast with the King Kong Salmonfly, and instantly the water erupted. Then again. And again. For the next hour, I caught fish on nearly every drift. In the chaos of rising trout and flying insects, I completely forgot about my feline fears—convinced the mountain lion was probably just sitting back, letting me have one last glorious moment before claiming his meal.
By the time I reached the truck, my hands were trembling from excitement. I’d finally experienced the iconic Salmonfly hatch—and it was every bit as wild as I’d imagined.

Stonefly Hatch Breakdown

I’ve included a seasonal breakdown of the most common stonefly hatches and fly selection and when they typically occur across different regions. Use it as a quick reference to help narrow down your fly selection and take some of the guesswork out of matching the hatch. With a bit of timing and observation, you’ll be ready for one of the most exciting and productive periods in fly fishing.

Black Stonefly (Winter Stonefly)

Read more about it here.

Brown Stonefly (Winter Stonefly)

Read more about it here.

Golden Stonefly

Read more about it here.

Yellow Sally Stonefly

Read more about it here.

Salmonfly or Giant Black Stonefly

Read more about it here.