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.
- 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 californica
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: 8 mm
A rather pale reddish brown species.
Head reddish brown; median carina and bases of antennae yellow. An oblique black line on each side of the face. Thorax reddish; mesonotum bright reddish brown. Mid-dorsal line of prothorax black; posterior margin white. Sternum and pleural sutures yellow with reddish brown marginings. Legs pale yellowish white; femora tinged with yellow. Wings hyaline. Longitudinal veins of the costal border yellowish; all others pale, except at extreme base, which are yellow. Stigmatic cross veins simple, curved, a few forked near the costal margin.
Segment 1 of abdomen largely opaque; 2-7 semi-hyaline; pale yellowish brown with smoky markings. Tergites 6 and 7, and segments 8-10, opaque reddish brown. Posterior margins of all segments smoky brown, this band darkest in the postero-lateral angles. Two oblique streaks on each side of each tergite, from the antero-lateral and postero-lateral angles. Mid-dorsal line pale, bordered by purplish submedian streaks. A dark line on the pleural fold.
Genitalia golden brown; tips of penes purplish brown. Forceps widened gradually toward the base. Penes separated by a rounded notch, into which projects a short blunt process from each division of the penes. Reflexed spur widest at base, its tip acute (see fig. 134). Tails pale smoky, darker at base.
Start a Discussion of Paraleptophlebia californica
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 californica
Species Range
Resources
- NatureServe
- Integrated Taxonomic Information System
- Global Biodiversity Information Facility
- Described by Traver (1934)