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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
Baetis

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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Dorsal view of a Siphlonurus quebecensis (Siphlonuridae) (Gray Drake) Mayfly Nymph from the Delaware River in New York
I photographed this nymph in the middle of molting between one instar and the next (not hatching).
Oldredbarn
Oldredbarn's profile picture
Novi, MI

Posts: 2600
Oldredbarn on May 12, 2010May 12th, 2010, 10:47 am EDT
Jason,

These are absolutely wonderful photos! What lens did you use?

I have always thought that when the mayfly molted it did it somehow along the same lines as when it's emerging in to the adult. Where the wing pad splits and they basically emerge through that opening. This appears more like a snake shedding its skin and it appears to have split along the bottom of the insect and the exuviae just flakes off.

The detail of the veins throughout is incredible.

I guess there is nothing "gray" about the younger version of the nymph, eh?! I hope you haven't started Spence in to thinking that he needs to tie up some transitional nymphs! It's bad enough now all the stages we are trying to imitate!

Spence
"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively

"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood

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