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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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Female Timpanoga hecuba (Great Red Quill) Mayfly Dun Pictures

This specimen is 14 mm. Technically this is the subspecies T. h. hecuba. The Cascades, Sierras and further West is where the other subspecies, T. h. pacifica is found. The Great Basin seems to have formed a barrier preventing any overlap in their distribution.

This mayfly was collected from Mystery Creek #178 in Idaho on September 15th, 2013 and added to Troutnut.com by Entoman on September 23rd, 2013.

Discussions of this Dun

Great Red Quill
19 replies
Posted by Entoman on Sep 22, 2013
Last reply on Oct 2, 2013 by Jmd123
This critter provided some excellent fishing a little after lunch the day this specimen was collected. They seem to be very delicate in handling as it expired inverted in the fly box while setting up for the photos. On this particular day the duns were up and away with little if any time spent on the water. The fish were feeding on ascending nymphs well below the surface. The hatch was a perfect fishing density and the fish were glutted with these large guys. To the naked eye they appeared chocolate brown with tan rings. The wings were a med. dun. Notice how stout their tapered abdomens are... Real chunks of protein!

The duns did not darken as they aged and as the photos show, there is little (if any) difference in the appearance between the dorsal and ventral surfaces. Very unusual for an ephemerellid...

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Female Timpanoga hecuba (Great Red Quill) Mayfly Dun Pictures

Collection details
Location: Mystery Creek #178, Idaho
Date: September 15th, 2013
Added to site: September 23rd, 2013
Author: Entoman
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