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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
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.

Dorsal view of a Ephemerella mucronata (Ephemerellidae) Mayfly Nymph from the Yakima River in Washington
This is an interesting one. Following the keys in Merritt R.W., Cummins, K.W., and Berg, M.B. (2019) and Jacobus et al. (2014), it keys clearly to Ephemerella. Jacobus et al provide a key to species, but some of the characteristics are tricky to interpret without illustrations. If I didn't make any mistakes, this one keys to Ephemerella mucronata, which has not previously been reported any closer to here than Montana and Alberta. The main character seems to fit well: "Abdominal terga with prominent, paired, subparallel, spiculate ridges." Several illustrations or descriptions of this holarctic species from the US and Europe seem to match, including the body length, tarsal claws and denticles, labial palp, and gill shapes. These sources include including Richard Allen's original description of this species in North America under the now-defunct name E. moffatae in Allen RK (1977) and the figures in this description of the species in Italy.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Mayfly Species Leucrocuta aphrodite (Pale Evening Duns)

This is one of the few Eastern species of the Heptagenia complex to produce fishable hatches.

Where & when

Time of year : Early May to early June

These hatches are sporadic.

In 32 records from GBIF, adults of this species have mostly been collected during June (38%), July (38%), August (13%), and May (9%).

In 6 records from GBIF, this species has been collected at elevations ranging from 881 to 1751 ft, with an average (median) of 1227 ft.

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

Described in Needham et al (1935) as Heptagenia aphrodite
Body length: 6 mm
Wing length: 7 mm

Mesonotum pale smoky brown; cross veins of costal area and some in wing disc margined with dark brown; tergites 2-6 pale yellowish dorsally and laterally, with broad dark lateral patches between; genitalia of the Leucrocuta maculipennis type.

Head pale yellow, shaded with orange or ruddy at base of ocelli and between these and eyes; anterior and posterior margins tinged with black. Pronotum pale yellow, tinged laterally with black. Mesonotum pale smoky brown, the lateral portion anterior to wings rather light ochreous; thus there appears to be a broad dark middorsal stripe containing a faint pale central line; scutellum pale whitish, a smoky brown area directly anterior to it. Pleura light yellowish; a broad blackish stripe above the leg bases. Sternum light yellowish. Legs pale yellowish; fore femora (usually not others) with a faint dark apical streak; fore tibiae and tarsi tinged with smoky. Wings hyaline; longitudinal veins fine, dark; cross veins heavier, those of the costal and subcostal spaces heavily dark-margined. Usually two veins in each of the first 6 or 7 spaces below the bulla are faintly heavier; a faint brown cloud at the fork of the posterior branch of the radial sector, 3 to 4 cross veins in costal space before the bulla, about 9 to 11 beyond it.

Abdominal tergite 1 deep brown except for the pale yellowish anterior margin. On tergites 2 and 3 are broad dark brown lateral patches, semi-rhomboidal with concave lateral edges; these do not quite reach the anterior margins of the tergites, but are joined by a narrow dark band on the posterior margin of each; thus a pale yellowish dorsal patch (larger on 3 than 2) and pale lateral areas remain on each of these tergites. The dark lateral patches on tergites 3-6 are smaller, semi-triangular, and the pale areas therefore larger. Tergites 7-10 deep black-brown. Sternites pale yellowish. Forceps and tails pale. Genitalia of the maculipennis type; apical projection of penes, as well as apical spines, stronger than in H. minerva (now a synonym of Leucrocuta minerva), but not as well developed as in H. hebe (now a synonym of Leucrocuta hebe). This species is rather intermediate between minerva and hebe, both in color characters and structural details of the penes. The lateral dark patches on the tergites are smaller than in hebe, but larger than in minerva.


Start a Discussion of Leucrocuta aphrodite

References

Mayfly Species Leucrocuta aphrodite (Pale Evening Duns)

Taxonomy
Species Range
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