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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.
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This species was fairly abundant in a February sample of the upper Yakima.
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Mayfly Genus Eurylophella (Chocolate Duns)
None of the species in this genus are recognized as significant hatches. Nevertheless, I have found their nymphs in my samples in many streams in both the East and Midwest.
Where & when
This genus is widespread throughout the East and Midwest but rarely abundant. The few species for which emergence dates are available all emerge in May and June.In 141 records from GBIF, adults of this genus have mostly been collected during June (46%), May (23%), July (20%), and April (6%).
In 44 records from GBIF, this genus has been collected at elevations ranging from 13 to 2723 ft, with an average (median) of 640 ft.
Genus Range
Nymph biology
Current speed: Slow
Specimens of the Mayfly Genus Eurylophella
3 Male Duns
I found this specimen along with a female on the surface in the shallows of a long flat in a warm-water smallmouth bass stream, during the middle of the afternoon. There were quite a few of them on the water throughout the day, but not enough to interest trout, especially since the nearest trout were several miles away in different rivers. I held on to this one for a few days hoping it would molt into a spinner for a better chance at a positive species ID, and it finally did, so this same individual is listed as a separate specimen as a spinner.
2 Female Duns
I found this specimen along with a male on the surface in the shallows of a long flat in a warm-water smallmouth bass stream, during the middle of the afternoon. This same individual is listed as a separate specimen after molting into a spinner.
4 Male Spinners
This male spinner molted from a dun I photographed a few days earlier, as did a female of the same species that I captured with it.
It keys confidently to Eurylophella temporalis using Allen & Edmunds (1963), primarily based on the shape of the penes, which is more distinctive for this species than for most others in the genus. However, the remainder of the description of the male spinner in that paper fits this specimen perfectly as well.
It keys confidently to Eurylophella temporalis using Allen & Edmunds (1963), primarily based on the shape of the penes, which is more distinctive for this species than for most others in the genus. However, the remainder of the description of the male spinner in that paper fits this specimen perfectly as well.
I wish I had photographed this one against a ruler or some kind of size reference. The genus ID is confident, and I am very tentatively calling it Eurylophella minimella based on the keys in Allen & Edmunds (1963) and the following judgment of its characteristics:
1. Has a "medium" rather than "large" tubercle on the styliger plate between the forceps bases (pretty sure)
2. Body and legs not sprinkled with fine brown dots (obvious)
3. Tails with dark annulations at the apex of each segment (obvious)
4. Terga brown and sterna pale; sterna 2-7 lacking large dark brown median macula, but each having 4 dark dots (pretty sure)
5. Penes widest near base, not mid-length (pretty sure)
6. Penes with a "shield-shaped" rather than "oblong" subapical excavation (not sure)
7. Dark brown apical macula on femora "distinct" rather than "faint" (very unsure on this judgment call)
If i'm wrong, i'm mostly likely wrong about point 7, which would make this Eurylophella verisimilis instead (forewings 8–9 mm long, vs 6–7 for minimella). If i'm wrong about point 6 (also very possible), the options would be Eurylophella aestiva and Eurylophella bicolor.
1. Has a "medium" rather than "large" tubercle on the styliger plate between the forceps bases (pretty sure)
2. Body and legs not sprinkled with fine brown dots (obvious)
3. Tails with dark annulations at the apex of each segment (obvious)
4. Terga brown and sterna pale; sterna 2-7 lacking large dark brown median macula, but each having 4 dark dots (pretty sure)
5. Penes widest near base, not mid-length (pretty sure)
6. Penes with a "shield-shaped" rather than "oblong" subapical excavation (not sure)
7. Dark brown apical macula on femora "distinct" rather than "faint" (very unsure on this judgment call)
If i'm wrong, i'm mostly likely wrong about point 7, which would make this Eurylophella verisimilis instead (forewings 8–9 mm long, vs 6–7 for minimella). If i'm wrong about point 6 (also very possible), the options would be Eurylophella aestiva and Eurylophella bicolor.
The genus ID on this specimen is confident but species is very tentative, based on the tentative ID of a seemingly-identical specimen from a nearby river a few days apart.
5 Female Spinners
This female spinner molted from a dun I photographed a few days earlier, as did a male of the same species that I captured with it.
I'm not sure of the species of this female spinner, and unfortunately I never found the associated males or duns to aid in identification. The egg-laying flight and fall of fairly large clouds of these females caused good rises of choosy trout for a week or so around early July on a large, cold spring creek in the northwoods. There is a distinctive stripe down the female's back, identical to that on this specimen collected a month later.
This Ephemerellidae spinner was emerging unusually late, and on a warm stream. Since it's a female, identification is difficult. Her identical coloration suggests she's probably of the same species as this specimen collected on a cool trout stream almost a month earlier.
I collected this uncooperative specimen as part of a small cloud of female spinners clustered tightly together high about 10 feet above the water, without any males that I could see.
15 Nymphs
Discussions of Eurylophella
florida mayfly nymph imitations
2 replies
Posted by Homer47 on Sep 5, 2012 in the species Eurylophella temporalis
Last reply on Sep 5, 2012 by Sayfu
Looks like an imitation would be about a #10 or #8 dark brown nymph pattern. I'm down here in north Fla and trying to match the hatch in the far north central part of the state, mostly to fool the bream. Any ideas or help would be appreciated. I found two patterns so far that seem to work- a little brown nymph with a rusty brown/orange thorax(maybe this is a good representation of the E. Temporalis), and a size 12 buzzer nymph with black body, peacock thorax and white breathing filament. The bream seemed to agree with that choice. I would like to try and copy more local insects as I figure out what they are.There are dragonflies and damselflies and mosquitoes. I could start there.
Start a Discussion of Eurylophella
References
- Caucci, Al and Nastasi, Bob. 2004. Hatches II. The Lyons Press.
- Knopp, Malcolm and Robert Cormier. 1997. Mayflies: An Angler's Study of Trout Water Ephemeroptera . The Lyons Press.
Mayfly Genus Eurylophella (Chocolate Duns)
Taxonomy
Species in Eurylophella
Eurylophella aestiva
0
0
Eurylophella bicolorChocolate Duns
0
0
Eurylophella doris
0
0
Eurylophella funeralis
0
0
Eurylophella lutulentaDirty Spiny Crawler Mayflies
0
0
Eurylophella minimella
2
25
Eurylophella prudentalis
0
0
Eurylophella temporalis
5
31
Eurylophella verisimilis
0
0
Species in Eurylophella: Eurylophella aestiva, Eurylophella bicolor, Eurylophella doris, Eurylophella funeralis, Eurylophella lutulenta, Eurylophella minimella, Eurylophella prudentalis, Eurylophella temporalis, Eurylophella verisimilis
5 species (Eurylophella bicoloroides, Eurylophella enoensis, Eurylophella lodi, Eurylophella macdunnoughi, and Eurylophella poconoensis) aren't included.