Hex Mayflies
Hexagenia limbata
The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
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 Leptophlebia bradleyi (Black Quills)
Where & when
In 1 records from GBIF, adults of this species have been collected during March (100%).
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: 9 mm
A dark brown species with yellowish wings; the femora black-ringed.
Head and thorax brown. Legs yellowish brown, with black rings on the apical third of all the femora. Wings hyaline, tinged with yellow. Veins brown. Costal cross veins numerous and distinct; stigmatic cross veins crowded and irregular, and anastomosed to form two rows of cells in the costal space, the outermost row being half the width of the inner one. Entire stigmatic area, and the radial space below it, semi-opaque, greyish.
Abdomen brown, darker at the ends. Tergites 1-8 with a narrow pale mid-dorsal line. On each side of this line are two rows of pale triangular spots, confluent on the basal margin. Ventrally paler, somewhat yellowish; ganglia not marked. Genitalia pale brown. Basal joint of the forceps slowly tapering and sinuately curved; the two small terminal segments dilated internally and subtriangular. Three short terminal joints are present, on one specimen. Penes long, tapering, separated by a V-shaped cleft for three-fourths of their length. Reflexed spur curved, spatulate, acute at the tip, reaching to the level of the bottom of the cleft (see fig. 134).
Start a Discussion of Leptophlebia bradleyi
References
- Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.
Mayfly Species Leptophlebia bradleyi (Black Quills)
Species Range
Resources
- NatureServe
- Integrated Taxonomic Information System
- Global Biodiversity Information Facility
- Described by Needham (1932)