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 Paraleptophlebia moerens
Where & when
In 13 records from GBIF, adults of this species have been collected during June (69%), May (15%), July (8%), and April (8%).
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: 6 mm
This is another small, clear-winged species with whitish, cross-lined abdomen. Head and thorax dark brown above. Legs pale. Wings whitish with a milky stigmatic area covering costal and subcostal interspaces. Costal cross veins almost wholly obsolete even in the stigmatic area where their faint vestiges are numerous, simple, and considerably aslant.
Abdomen brown on the ends; segments whitish on 3 to 6; less so on 2 and 7. The dorsal apical cross-bands of the white segments are well marked, as are also the lateral, longitudinal, spiracular lines which meet them at the hind angle of the segments. Forceps with a large basal lobe-like dilatation of its first segment. Penes separated for half their length by an oval notch, the aperture of which is closed by a lobe-like prolongation inward of their distal ends. Outer angle of the tips broadly rounded. The proximal portion of its margin is prolonged forward in an incurved spine; attached to this spine is the usual reflexed spur which is very slender (see fig. 133). Tails white.
Start a Discussion of Paraleptophlebia moerens
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 Paraleptophlebia moerens
Species Range
Resources
- NatureServe
- Integrated Taxonomic Information System
- Global Biodiversity Information Facility
- Described by McDunnough (1924)