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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.

Lateral view of a Clostoeca disjuncta (Limnephilidae) (Northern Caddisfly) Caddisfly Larva from the Yakima River in Washington
This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
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 Eurylophella funeralis (Chocolate Duns)

According to the Leonards in Mayflies: An Angler's Study of Trout Water Ephemeroptera , this species and Eurylophella bicolor are the two most likely hatches for fly fishermen to encounter in Michigan. Based on my sampling, it seems other species may be more prevalent elsewhere.

Where & when

Time of year : May and June

In 12 records from GBIF, adults of this species have been collected during May (67%), June (25%), and July (8%).

In 1 record from GBIF, this species has been collected at elevation of 194 ft.

Species Range

Hatching behavior

Time of day : Early afternoon

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 Ephemerella funeralis
Body length: 7.5-9 mm
Wing length: 9 mm

A species of the bicolor group (now a synonym of Eurylophella bicolor), quite close to E. temporalis (now a synonym of Eurylophella temporalis), but considerably darker.

Eyes orange. Head yellowish brown; a black spot below each antenna, next to eye. Vertex shaded with blackish. Head of female deep yellow, vertex brown. Thorax reddish brown. A median depressed O-shaped area on the pronotum, sometimes outlined in rose color; on the anterior margin the lateral carinae around this depression run up into a spine. A rose-colored mark near the lateral margin on each side; blackish pencilings near the median line. Mesonotum yellowish laterally; median line dark red; a median geminate black streak just anterior to the scutellum. A blackish streak before each wing root, surrounded by a yellow area. Coxae brown-tinged, with a purplish black transverse streak. Fore leg amber, other legs paler yellow; claws and tips of last tarsal joint dusky. Wings hyaline; venation pale, the main veins of the costal margin yellowish.

Abdominal tergites reddish brown, 8-10 darker. Posterior margins, pleural fold, lateral streaks, a narrow median line, subdorsal streaks and stigmatic marks blackish brown. A pale yellowish area on each side of the dark mid-dorsal line. Sternites somewhat paler reddish brown. Oblique black dashes and dark dots distinct. Ganglionic areas blackish brown, on middle sternites. Tails yellowish brown at the base, whitish apically; joinings purplish black. Genitalia dark reddish brown.

Nymph

Described in Needham et al (1935) as Ephemerella funeralis

Occipital tubercles of the nymph well developed, rounded. The rows of dorsal spines diverge distinctly to rearward. The spines on tergites 1-3 are thin, tapering and very erect. The lateral extensions and postero-lateral spines are better developed in this species than in any other of the bicolor group (now a synonym of Eurylophella bicolor); the spine on segment 9 is fully twice as long as its width at the base. The lateral margins of segment 9 are subparallel, the spines at the tip being distinctly incurved. General color brown, rather unicolorous; markings of the femora very indistinct; operculum unmarked or with faint pale dots. The usual curved row of dark dots on the sternites is absent, but the short dark oblique dashes are present. Tails unicolorous brown; joinings of a few of the basal segments darker brown.


Start a Discussion of Eurylophella funeralis

References

Mayfly Species Eurylophella funeralis (Chocolate Duns)

Species Range
Common Name
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