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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Dorsal view of a Grammotaulius betteni (Limnephilidae) (Northern Caddisfly) Caddisfly Larva from the Yakima River in Washington
This is a striking caddis larva with an interesting color pattern on the head. Here are some characteristics I was able to see under the microscope, but could not easily expose for a picture:
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Report at a Glance

General RegionNortheast Idaho and southern Montana
Specific LocationHenry's Fork & Madison River
Dates FishedJuly 15 thru July 20th, 2007
Time of DayMornings, afternoons and evenings
Fish CaughtRainbow trout
Conditions & HatchesHot, hot and very dry!!! Water flow was up around 1500 CFS so the fishing was tough in some areas. PMDs, Flavs, Spotted Sedge and some Callibaetis

Details and Discussion

Wiflyfisher's profile picture

Posts: 622
Wiflyfisher on Jul 24, 2007July 24th, 2007, 3:44 pm EDT
Big trout and little flies.... sporadic hatching and knowing where to fish really helps find the big fish. Figuring out which fly and what stage the big bows were feeding on was a real (and fun) challenge. At times surrounded by rising trout and other times nothing moving.
Site Editor
"Bear Swamp," PA

Posts: 1681
GONZO on Jul 24, 2007July 24th, 2007, 3:55 pm EDT
John, despite the heat, I can tell you're having a great time on the Fork (and elsewhere). Of course, that was a given wasn't it? Give 'em hell, pal! Make us jealous! :)
Wiflyfisher's profile picture

Posts: 622
Wiflyfisher on Jul 24, 2007July 24th, 2007, 4:09 pm EDT
Lloyd, I stood on the bank and watched a big #$%^&@! trout (around 25") sliding in and out 15 feet from shore sipping something in that appeared invisible to the human eye. Sometimes the fish would open it's mouth underneath the water and suck something in and other times it would slowly tips it's nose to the surface and quietly slurp something in. (This was all while the winds were blowing too!)

Needless to say, I worked that fish for close to an hour, got him to look at a couple of emergers and pheasant tail nymphs but in the end nada! It was "extremely tough" with the blowing wind to present the fly in a real natural manner (without any drag) and in his tight feeding lane. But it was still awesome to watch!!!
Martinlf's profile picture
Palmyra PA

Posts: 3047
Martinlf on Jul 24, 2007July 24th, 2007, 4:31 pm EDT
John, I worked a small brown today on the Little Lehigh under similar conditions, wind, tight feeding lane, tough lie for a drift. I never got a fly to him that he would take either. I'm pleased to have had the challenge, though, and hope to work out a solution that in similar conditions will get a rise in the future. It's these fish that really get us determined. I'm sure you are catching some nice fish, though, and having fun. Stick one for us!
"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell

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