The runoff has subsided and the streams are starting to clear up so fishing should be starting to improve. Every June it seems there are so many places to fish, so many different hatches, and so little time to fish.
Around the Sheridan area the possibilities are quite enticing: caddis hatches around dusk on many of the plains streams, late afternoon gray drake hatches on the plains and canyon streams, and, finally, brown stonefly hatches during midday on the canyon streams.
Of course, the salmon fly hatches start around this time in Montana and the famous green drake hatch gets under way on the Henry's Fork of the Snake in Idaho.
Since the hatches in Montana and Idaho are a bit of a drive, it would make sense to take advantage of those closer to home.
Of all the insect hatches that occur locally each year, I must admit that the brown stonefly hatch is as enjoyable and exciting as any hatch I have fished anywhere. While the Bighorn Mountain streams don't usually hold monster trout, they do contain some decent fish. If a fly fisher is going to catch a 3-pound trout on a dry fly, it is a good bet that he/she will do it during the brown stonefly hatch.
During normal runoff years, the brown stoneflies don't start emerging until late June, but during low runoff years the hatch can start in mid-June and be over by July 1. This year seems to be more along the latter category. It seems that with lower flows, the water warms up quicker and the stoneflies need so many degree-days to hatch — warmer water means the degree-day total is reached more quickly.
Just as the salmon flies and other big stoneflies, the brown stoneflies crawl to the edge of the stream and usually emerge onto the bank or a rock, shed their nymphal exoskeleton and clamber onto a rock or bush. The stoneflies mate and then the female returns to lay eggs in the stream. She flies along the stream and briefly hovers over the water while she plunges her ovipositor into the water to extrude some eggs. Then she flies further to deposit some more eggs.
While brown stoneflies aren't as big as salmon flies, they are still quite substantial. The female is about 1 ½ inches long while the male is about an inch long. Suffice it to say that the trout look for the skittering stoneflies and go after them very aggressively.
One of my first encounters with a brown stonefly hatch occurred about 20 years ago. I was guiding two anglers from New Jersey, and we had driven to a canyon stream. It was late morning when we arrived and I was amazed to see a lot of cottonwood fluff in the air — especially when there were mostly ponderosa pines growing along the stream.
"Look at all the cottonwood fluff in the air," I exclaimed.
My tactful angler responded, "If it's cotton, why is it flying against the wind?"
I guess that will give you an idea of how plentiful the stoneflies can be.
That day my anglers managed to catch a bevy of trout ranging from 8 to 17 inches. I have gone back to that spot several times and have had similarly successful days.
To imitate the brown stonefly, try using a size 8 yellow stimulator. If you tie your own flies, tie a stimulator with a tan body rather than yellow.
You can fish the stimulator dead drift, and if that method doesn't yield great results, try twitching the fly or skating it. The latter method may result in a strike roughly akin to a 10-pound bag of sugar being dropped onto the fly.
I forgot to mention that after the brown stonefly hatch dies down, the gray drakes start coming off later in the afternoon. This size 10-12 mayfly is pretty substantial, too, so if you haven't had your fill of dry fly fishing fun, tie on a big blue dun and have at those trout for a few more hours. Just remember to quit before dark so you won't have to worry about the caddis hatch!
Well, another weekend is creeping up on us. With improving water conditions and lots of aquatic insects emerging, the fishing should be great for the next month, but perhaps you should get out early and fish often to fully enjoy the hatches. Remember the good fishing only comes to those who go fishing.
Bob Krumm, of Sheridan, is the Wyoming outdoor correspondent for The Billings Gazette. Contact him at firstname.lastname@example.org.