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.
- 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.
Mayfly Species Siphlonurus barbarus (Gray Drakes)
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: 11 mm
A medium-sized species resembling S. berenice (now a synonym of Siphlonurus typicus), but with more clearly defined ventral markings.
Head brown, frontal margin pale. Thorax brown; pleural sutures pale yellowish. Legs pale yellowish brown, the fore legs somewhat darker. Tips of femora and tarsal joinings dark brown. Wings hyaline; veins brown.
Abdomen brown dorsally; anterior margin of each tergite semi-translucent, yellowish. Traces of dark dorsal and submedian longitudinal dashes visible on the posterior tergites. Pale yellowish ventrally. Lateral dark patches present. Sternite 9 largely dark brown. Forceps base pale yellowish; forceps smoky brown. Tails pale yellowish, joinings brown. Penes shown in fig. 122.
Start a Discussion of Siphlonurus barbarus
References
- Merritt R.W., Cummins, K.W., and Berg, M.B. 2019. An Introduction to the Aquatic Insects of North America (Fifth Edition). Kendall/Hunt Publishing Company.
- Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.
Mayfly Species Siphlonurus barbarus (Gray Drakes)
Species Range
Common Names
Resources
- NatureServe
- Integrated Taxonomic Information System
- Global Biodiversity Information Facility
- Described by McDunnough (1924)