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.
I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.
The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.
Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
Mayfly Species Macdunnoa persimplex
Species Range
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
Wing length: 7.5 mm
A small pale species; genitalia distinctive; it may be allied to Heptagenia elegantula (see fig. 95).
Eyes widely separated; vertex of head between eyes bright yellow, becoming pale creamy below antennae. Thorax creamy; yellowish tinges on pleura or bases of fore legs. Legs pale yellowish, shading into dirty whitish on tibiae and tarsi. Fore tibia smoky at apex; fore tarsus distinctly longer than tibia; basal tarsal joint normally about 1/3 the length of the second; second subequal to third, twice as long as fourth; fifth about as long as first. Considerable variation exists, in different specimens, however, as to the relative lengths of the fore tarsal joints. Wings hyaline; cross veins dark. 5 to 6 basal costal cross veins; stigmatic cross veins somewhat thicker than the others, but not as much so as in Anepeorus simplex (now a synonym of Spinadis simplex) which is superficially very similar to the present species.
Abdomen pale creamy; segments 1-7 hyaline, 8-10 opaque. Tails whitish. Apical margin of forceps base rather deeply excavated; penes slightly resemble those of H. elegantula on the one hand, and those of the H. lucidipennis (now a synonym of Nixe lucidipennis) group on the other. Forceps joints, however, as in the former species.
Start a Discussion of Macdunnoa persimplex
References
- Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.
Mayfly Species Macdunnoa persimplex
Species Range
Resources
- NatureServe
- Integrated Taxonomic Information System
- Global Biodiversity Information Facility
- Described by McDunnough (1929)