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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.

Lateral view of a Psychodidae True Fly Larva from Mystery Creek #308 in Washington
This wild-looking little thing completely puzzled me. At first I was thinking beetle or month larva, until I got a look at the pictures on the computer screen. I made a couple of incorrect guesses before entomologist Greg Courtney pointed me in the right direction with Psychodidae. He suggested a possible genus of Thornburghiella, but could not rule out some other members of the tribe Pericomini.
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.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Mayfly Species Paraleptophlebia sculleni

Where & when

Time of year : Summer

To my knowledge, this species has only been described in the scientific literature from the Oregon Cascades. However, on July 25th, I found several swarms of a dozen or so male spinners dancing above a gravel road/trail on the rim of a bouldery canyon at 2800 feet elevation on the eastern slope of the Washington Cascades.

Although this canyon would easily constitute class 4+ whitewater when flows are higher, at typically low summer flows there are lots of quiet backwaters in the pools between the fast drops and boulders. This might be the habitat for the Paraleptophlebia nymphs.

I found them again a couple weeks later on the Middle Fork Snoqualmie River on the west slope of the Washington Cascades.

In 7 records from GBIF, adults of this species have been collected during June (43%), July (29%), and August (29%).

Species Range

Spinner behavior

The male spinners I encountered were flying right at dusk.

Physical description

Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.

Male Spinner

Body length: 6.5 mm
Wing length: 6.5 mm

This is another brown and white, clear-winged species with black-ringed abdomen. Thorax brown above with paler sutural lines on the sides. Legs pale. Wings hyaline. Costal cross veins obsolete except in the creamy stigmatic area which covers costal and subcostal interspaces. Stigmatic cross veins few, simple, slightly curved.

Abdomen brown on segments 1 and 8 to 10; light brown on 2 and 7; white on 3 to 6, and on the base of 7, with blackish apical half-rings and lateral stripes that are darker at the postero-lateral angles of the segment. Ganglia and venter of segments 7 to 9 yellowish. The basal segment of the forceps tapers suddenly at the base, then very slightly to its tip. The penes are separated by an oval U-shaped notch, longest at the inner angle which projects rearward in a rounded lobe. Lateral to this lobe the apex is obliquely truncate, ending laterally in a minute recurved hook; the reflexed spurs are elongate, sickle-shaped and incurving at the tip (see fig. 133).

Specimens of the Mayfly Species Paraleptophlebia sculleni

2 Male Spinners

Start a Discussion of Paraleptophlebia sculleni


  • Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.

Mayfly Species Paraleptophlebia sculleni

Species Range
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