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.
Featured on the forum
This specimen keys to the Epeorus albertae group of species. Of the five species in that group, the two known in Washington state are Epeorus albertae and Epeorus dulciana. Of the two, albertae has been collected in vastly more locations in Washington than dulciana, suggesting it is far more common. On that basis alone I'm tentatively putting this nymph in albertae, with the large caveat that there's no real information to rule out dulciana.
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Mayfly Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)
The Ephemerellidae are undoubtedly the most important family of mayflies for the American trout angler. Most species known as Hendricksons, Pale Morning Duns and Sulphurs belong to the genus Ephemerella in this family, while the genus Drunella lays claim to many Eastern and Western Blue-Winged Olives and the Western Green Drakes.
Where & when
Ephemerellids can be found in virtually any cold water habitat across the continent. A curious fact about this family is that the males and females often inhabit different parts of the stream. In many species, the males and females are of different sizes and colors, and your fly may need to match the dominant gender emerging from your stretch of the river.In 532 records from GBIF, adults of this family have mostly been collected during June (36%), July (25%), May (17%), April (8%), and August (6%).
In 798 records from GBIF, this family has been collected at elevations ranging from 3 to 11601 ft, with an average (median) of 1444 ft.
Family Range
Hatching behavior
These are fantastic dry-fly insects. Behavior varies by species, but almost all have excellent qualities for the angler. Most eclode laboriously in the surface film, where emerger and floating nymph patterns are excellent. Others before reaching the surface, making them good wet-fly fare. Some species have been documented to engage in both forms thus opening debate over whether these two styles of emergence are driven by genetics or environmental influences. They can also take a very long time to prepare their wings for flight once they reach the surface. There they ride like miniature sailboats in the classic mayfly style, fluttering occasionally, and can be imitated by a plethora of upright winged dry fly patterns.Many species are especially prone to being stillborn or crippled, and trout are especially fond of this wounded prey and can be fooled by our crafty imitations.
Spinner behavior
Most species return to the stream as spinners one day after they emerge. Spinner falls are usually concentrated over the riffles, but occur over selected stretches on waters lacking this feature.Nymph biology
Nymphs of this family are a gift to the angler, because many have the peculiar habit of swimming up and down between the surface and the bottom several times before actually emerging. The actual biological purpose these seeming "practice runs" serve is open to debate, but they expose the slow-swimming nymphs to the trout. This behavior has been described by biologists as pulses of benthic drift, and they can do so in astounding numbers. They do the same near the surface as well.Several authors write that some of the nymphs crawl to the high tips of rocks and other objects prior to emergence, where they may be picked off their perches by peckish trout. During the spring months, they can often be found grazing in such exposed locations even when they aren't about to emerge.
Between their tendency to be in exposed places and behavioral drift, the nymphs of this family are important to trout year-round. Their imitations often prove successful anywhere in the water column.
Identification
To determine whether a specimen of Ephemeroptera belongs to Ephemerellidae, use the Key to Families of Mayfly Nymphs or Key to Families of Mayfly Duns and Spinners.
Specimens of the Mayfly Family Ephemerellidae
15 Male Duns
This dun is smaller than would normally be expected for Drunella flavilinea, but it seems to fit the physical description of that species fairly well. I wasn't sure from the dun pictures alone, so I was hoping it would molt into a spinner. It never made it out of the dun's shuck, but it did begin the process, which allowed me with great care to tease out the last couple abdominal segments of the spinner from the still tightly attached dun shuck, enabling a more confident ID based on the shape of the spinner's penes and sub-genital plate. I also collected a nymph of flavilinea in the same river on the same evening, as well as a shed exuvium that looked large enough to belong to an emerging dun.
The other possibility I considered for a while based on the dun was Drunella pelosa, which would be the right size, but the other characteristics don't fit.
The other possibility I considered for a while based on the dun was Drunella pelosa, which would be the right size, but the other characteristics don't fit.
The positive species ID on this dun comes from both the spinner that it (or possibly one other dun just like it) molted into and the overwhelming abundance of nymphs of this species in my kicknet samples from the same site.
This dun hatched in my aquarium on July 16th from an easily identified nymph collected on July 10th, and it molted into a spinner after I photographed it. The beautiful spinner form is listed as separate specimen. I forgot to photograph the dun with the ruler, but naturally his size is pretty similar to what it was as a spinner.
A few days after unexpectedly collecting a female dun of this species, but in a sad, bedraggled shape, I went back to the same pool to see if I could find more. I was able to catch this one male dun during a dusk emergence dominated by other species, and he made it home in prime shape for photos.
I collected this male Hendrickson dun and a female in the pool on the Beaverkill where the popular Hendrickson pattern was first created. He is descended from mayfly royalty.
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.
This dun was collected in proximity to this spinner.
This dun was collected in proximity to this spinner, and to this female that looks like the same species.
Among western species, it most closely resembles Ephemerella aurivillii, of which I reared a specimen from a positively-identified nymph and photographed the male dun previously in Alaska. In the photos, this dun does not seem to have the same evidence of the nymph's dorsal stripe, but that's due to the lighting. A faint stripe is apparent under the microscope, as it is in the female linked above.
They do appear to be a bit short for aurivillii, with the male at 8 mm and the female at 9 mm, but the spinners could be a bit longer.
Among the other Ephemerella mayflies documented in Montana, Ephemerella alleni and Ephemerella mucronata are the only two others that seem to not be ruled out.
Among western species, it most closely resembles Ephemerella aurivillii, of which I reared a specimen from a positively-identified nymph and photographed the male dun previously in Alaska. In the photos, this dun does not seem to have the same evidence of the nymph's dorsal stripe, but that's due to the lighting. A faint stripe is apparent under the microscope, as it is in the female linked above.
They do appear to be a bit short for aurivillii, with the male at 8 mm and the female at 9 mm, but the spinners could be a bit longer.
Among the other Ephemerella mayflies documented in Montana, Ephemerella alleni and Ephemerella mucronata are the only two others that seem to not be ruled out.
15 Female Duns
I'm fairly confident calling this dun Ephemerella tibialis because it emerged from one of several similar nymphs in my bucket, which I was able to ID with quite a bit of certainty. However, it looks very different from the other duns I currently have listed, which makes me rethink their IDs.
Although there is no key to female duns, I'm calling this dun Ephemerella excrucians because I collected several mature nymphs of that species on the same trip.
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.
This "specimen" is actually two different duns, one missing the middle front and back left legs, the other missing the terminal filament i.e. middle tail. I added them together by accident, but since they're the same species, stage, and gender, I might as well leave them together.
I didn't find a male spinner to associate with this one; I'm tentatively calling it grandis based on size alone. I found it floating down the surface of the Henry's Fork (the only one I saw that day, weeks after the hatch probably peaked) crippled by what appears to be a mass of eggs sticking out of its abdomen.
This female was collected in proximity to a male that looks like the same species.
I don't know for sure that this is Drunella tuberculata, but that's my best guess for now.
It certainly has a different look and much more robust body shape from Drunella lata duns I photographed a couple weeks earlier, so I doubt it's that species. Using distribution records to eliminate other choices narrows this down to Drunella tuberculata or Drunella walkeri.
Markings described for the abdominal sternites of the male spinner of Drunella tuberculata are suspiciously similar to those on this female dun. Also, this dun is 9.5mm long (my ruler pic isn't very good, but I'm basing this on measuring the real thing). The size range given in the old Allen & Edmunds keys for walkeri females is 7-8mm, while tuberculata is 9-11mm. For these reasons I'm sticking it in tuberculata for now.
This is the only Drunella mayfly I saw all day. I scooped it off the water as it emerged at around 7pm from a big Catskill tailwater.
It certainly has a different look and much more robust body shape from Drunella lata duns I photographed a couple weeks earlier, so I doubt it's that species. Using distribution records to eliminate other choices narrows this down to Drunella tuberculata or Drunella walkeri.
Markings described for the abdominal sternites of the male spinner of Drunella tuberculata are suspiciously similar to those on this female dun. Also, this dun is 9.5mm long (my ruler pic isn't very good, but I'm basing this on measuring the real thing). The size range given in the old Allen & Edmunds keys for walkeri females is 7-8mm, while tuberculata is 9-11mm. For these reasons I'm sticking it in tuberculata for now.
This is the only Drunella mayfly I saw all day. I scooped it off the water as it emerged at around 7pm from a big Catskill tailwater.
I collected this female Hendrickson dun and a male in the pool on the Beaverkill where the popular Hendrickson pattern was first created. She is descended from mayfly royalty.
I can't be certain of the ID of this female dun, but I'm calling it Drunella flavilinea for three reasons: 1) the known abundance of "flavs" on the Henry's Fork, 2) clear differences in coloration from my confirmed specimens of Drunella coloradensis, which is the main lookalike, and 3) the habitat (a sizable river in a wide mountain valley, rather than a small, high-altitude stream) suggests it's not coloradensis.
This one was collected in association with a male spinner, but they appear to be different families.
13 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.
This spinner molted from this dun, or possibly one other dun I had in the same container that looked just like it.
This spinner molted from a dun after being photographed, and the dun form is listed here as a separate specimen. I've rarely found a more cooperative and photogenic mayfly.
This spinner was collected in proximity to this dun and this other dun, so one of them is likely the same species. Note for ID purposes that this one is missing one of its cerci.
I collected this beautiful male Hendrickson specimen as a dun, along with a female Hendrickson from the same hatch. Both molted into spinners in my house within a couple of days.
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.
15 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 calling this one Ephemerella dorothea infrequens because it was collected along with two males that positively ID to that species.
I've seen Ephemerella invaria with green egg sacs and Ephemerella subvaria with yellow one. This one seems too large for dorothea. So what is it? I'm not sure.
Many females of this species were gathered in tight clouds to lay their eggs over the riffles in a mid-sized Pocono stream right at dusk. It would have been a fishable spinner fall if I'd stuck around to wait for them.
Many females of this species were gathered in tight clouds to lay their eggs over the riffles in a mid-sized Pocono stream right at dusk. It would have been a fishable spinner fall if I'd stuck around to wait for them.
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.
This female Hendrickson spinner is in kind of bad shape, but at least now I've got some good closeup photos of one. I collected her and a male Hendrickson as duns from the same hatch, and both molted into spinners in my house within a couple of days.
15 Nymphs
In a bucket full of Drunella coloradensis nymphs, this was the only specimen of Drunella spinifera (and the first one I've found anywhere).
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.
This one nicely illustrates the variation in coloration within an single Ephemerellid species in a single stream, when compared to its darker, more uniform counterpart.
I've never seen this strange coloration on any Ephemerella subvaria nymph in a book before, but it's similar to several other specimens I collected on the same outing, including a smaller one that I photographed. They were outnumbered by the "normal" Ephemerella subvaria nymphs in the sample.
11 Streamside Pictures of Ephemerellidae Mayflies:
This Ephemerella invaria sulphur dun got stuck in its shuck trying to emerge. This isn't exactly a "natural" pose for a photograph, but it kind of shows what an emerger pattern could look like.
In this picture: Mayfly Species Ephemerella invaria (Sulphur).
Here's an above-the-water view of a stillborn Ephemerella subvaria dun which I also photographed from below the water.
In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
Here's a fresh ball of eggs from a Hendrickson spinner, photographed to show the proper color for the egg-ball on spinner patterns.
In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
A freshly emerged female Drunella cornuta dun.
In this picture: Mayfly Species Drunella lata (Small Blue-Winged Olive).
The underside of a freshly emerged Ephemerella invaria dun.
In this picture: Mayfly Species Ephemerella invaria (Sulphur).
Shed exoskeleton from what was very likely an Ephemerella aurivillii nymph that emerged on this rock.
In this picture: Mayfly Species Ephemerella aurivillii.
Here's the bottom of a freshly emerged male Drunella cornuta dun, showing a lighter shade of olive than the specimens I photographed with my better camera in the evening.
In this picture: Mayfly Species Drunella lata (Small Blue-Winged Olive).
18 Underwater Pictures of Ephemerellidae Mayflies:
This is a close-up underwater view of a stillborn Ephemerella subvaria (Henrickson) female dun.
In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
This picture from below shows a stillborn Ephemerella subvaria (Hendrickson) dun drifting on the surface amidst a number of shed pupal skins from Brachycentrus caddisflies which were heavily hatching that day.
There's a large Ephemerella subvaria nymph in the top left.
The white blotches on this rock are Leucotrichia caddisfly cases, and the wispy tubes are cases made by a type of midge.
Some large Ephemerella mayfly nymphs cling to a log. In the background, hundreds of Simuliidae black fly larvae swing in large clusters in the current.
Three big Ephemerella subvaria mayfly nymphs share a rock with some cased caddis larvae.
This Ephemerella subvaria (Hendrickson) nymph picture is one of my favorites.
In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
The mayfly and stonefly nymphs in this picture blend in extremely well.
In this picture: Mayfly Species Ephemerella invaria (Sulphur) and Insect Order Plecoptera (Stonefly).
A large Ephemerella subvaria nymphs clings to a log along with a couple smaller mayfly nymphs.
In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
A couple Sulphur (Ephemerella invaria) nymphs cling to a log.
In this picture: Mayfly Species Ephemerella invaria (Sulphur).
This log houses several Ephemerella mayfly nymphs and, on the top right, an Epeorus mayfly nymph.
In this picture: Mayfly Species Ephemerella invaria (Sulphur) and Mayfly Genus Epeorus (Little Maryatt).
An Ephemerella subvaria nymph clings to a white rock in the foreground, and there are other nymphs in the background.
In this picture: Mayfly Species Ephemerella subvaria (Hendrickson) and Insect Order Trichoptera (Caddisfly).
Discussions of Ephemerellidae
PMD Spinner - Egg sack color?
20 replies
Posted by Wbranch on Jan 26, 2010 in the species Ephemerella excrucians
Last reply on Aug 18, 2020 by Troutnut
Do any of you entomologist types know the true color of the PMD spinner? Dorothea or excrucians. Where I fish in MT there are huge spinner falls, many spents are on the water in the morning and others fall again at various periods during the day. I'd like to tie some with egg sacks as I saw many in July but forgot what color they were. Thanks.
rotunda
8 replies
Posted by CharlieBugs on Jan 25, 2015 in the species Ephemerella invaria
Last reply on Feb 1, 2015 by Gutcutter
Your post on Ephemerella subvaria brought back some memories that might be of interest to some readers.
I got my master’s degree under Ed Cooper at Penn State in 1966. I studied the impact of low oxygen from Penn State’s sewage plant on the mayflies of Spring Creek. The plant mostly removed BOD (organic matter which causes low oxygen) by oxidizing it in a bacteria rich environment. But at that time the plant did not remove phosphorus (and nitrogen) which fertilized the macrophytic algae and other plant growth. There were far more macrophytes (large plants) in Spring Creek below the sewage plant entrance than above, and essentially no mayflies. What was there in the effluent that killed the mayflies? Mayflies put directly in the effluent did not die over a 16 hour day. But oxygen samples taken over 24 hours in summer showed a much greater variation below the effluent (from 16 ppm (or mg/l), 160% of saturation in late afternoon) to 3 ppm (30 percent saturation just before dawn) (vs 14 to 10 ppm, +- 20 percent saturation above the effluent.
I built a Rube Goldberg machine in the lab that would control the oxygen levels and temperature of control and experimental cages that each held 25 mayflies. The control would keep oxygen near saturation and the experimental one would lower the oxygen over 8 hours (the length of night in summer). Mortality was dependent upon both oxygen level and temperature. Virtually no mayflies would die if the oxygen was above 2 PPM (or mg/l) at 8 C, or at 4.5 at 20 C. Seventy five percent of larvae would die at 1 ppm at 8 degrees and 2.5 ppm at 20 degrees. So the mortality was much more if the temperatures were high. Hence most of the mortality would presumably occur in August when the high temperatures (20C) would increase the larvae metabolism and hence need for oxygen, but the water would hold less oxygen even before the night-time respiration of the macrophytes would reduce it much further (to only 3 ppm). Thus the low nighttime oxygen caused by excessive plant growth was a sufficient cause or the near total absence of mayflies below the sewage plant. Recognizing the aquatic impact Penn State started to use land disposal of its effluent which as far as I knew alleviated, and even stopped, the negative impacts on the mayflies. Can anyone verify this ? The otherwise well done “The Fishery of Spring Creek; A Watershed Under Siege “
By Robert F. Carline, Rebecca L. Dunlap Jason E. Detar, Bruce A. Hollender Has nothing on dissolved oxygen or aquatic insects. In my opinion we need much more of an ecosystems approach for streams (Which we are doing for Little Sandy Creek in N.Y.).
Now back to Ephemeralla subvaria. The title of the paper I published on this project (my first of nearly 300 publications) was:
1. Hall, C.A.S. 1969. Mortality of the mayfly nymph, Ephemerella rotunda, at low dissolved oxygen concentrations. J. Elisha Mitchell Sci. Soc. 85(1): 34-39 (M.S. Thesis, Pennsylvania State University, 1966).
Whoa! Ephemeralla rotunda? This was by far the most abundant mayfly in Spring Creek where I sampled! But I could not even find the name in your list. Also I had my samples verified by Burke, author of the authoritative "Mayflies of Illinois", and he said Well that’s what it keyed out to in my book”. (Talk about scientific ass covering! ) Well to make matters worse (as of 24 hours ago) my next girlfriend, Molly, at the University of North Carolina, loved the name of “Ephemerella rotunda”, the rotund one, which comes to think of it described her as well. I liked it too. But n’exist plus: where had the most abundant mayfly gone? Fortunately upon reading the rest of the post I found “Ephemerella invaria is one of the two species frequently known as Sulphurs (the other is Ephemerella dorothea). There used to be a third, Ephemerella rotunda, but entomologists recently discovered that invaria and rotunda are a single species with an incredible range of individual variation." Ahh neither rotunda nor Molly stood the test of time. So I assume what I called rotunda is still alive and well in Spring Creek as invaria. Again, can anyone verify that?
If anyone wants to follow up on the distribution and abundance of mayfly (or any other species) may I recommend: Hall, C.A.S., J.A. Stanford and R. Hauer. 1992. The distribution and abundance of organisms as a consequence of energy balances along multiple environmental gradients. Oikos 65: 377-390. I can send it if you cannot get it from google, which I think you can. (chall@esf.edu)
I got my master’s degree under Ed Cooper at Penn State in 1966. I studied the impact of low oxygen from Penn State’s sewage plant on the mayflies of Spring Creek. The plant mostly removed BOD (organic matter which causes low oxygen) by oxidizing it in a bacteria rich environment. But at that time the plant did not remove phosphorus (and nitrogen) which fertilized the macrophytic algae and other plant growth. There were far more macrophytes (large plants) in Spring Creek below the sewage plant entrance than above, and essentially no mayflies. What was there in the effluent that killed the mayflies? Mayflies put directly in the effluent did not die over a 16 hour day. But oxygen samples taken over 24 hours in summer showed a much greater variation below the effluent (from 16 ppm (or mg/l), 160% of saturation in late afternoon) to 3 ppm (30 percent saturation just before dawn) (vs 14 to 10 ppm, +- 20 percent saturation above the effluent.
I built a Rube Goldberg machine in the lab that would control the oxygen levels and temperature of control and experimental cages that each held 25 mayflies. The control would keep oxygen near saturation and the experimental one would lower the oxygen over 8 hours (the length of night in summer). Mortality was dependent upon both oxygen level and temperature. Virtually no mayflies would die if the oxygen was above 2 PPM (or mg/l) at 8 C, or at 4.5 at 20 C. Seventy five percent of larvae would die at 1 ppm at 8 degrees and 2.5 ppm at 20 degrees. So the mortality was much more if the temperatures were high. Hence most of the mortality would presumably occur in August when the high temperatures (20C) would increase the larvae metabolism and hence need for oxygen, but the water would hold less oxygen even before the night-time respiration of the macrophytes would reduce it much further (to only 3 ppm). Thus the low nighttime oxygen caused by excessive plant growth was a sufficient cause or the near total absence of mayflies below the sewage plant. Recognizing the aquatic impact Penn State started to use land disposal of its effluent which as far as I knew alleviated, and even stopped, the negative impacts on the mayflies. Can anyone verify this ? The otherwise well done “The Fishery of Spring Creek; A Watershed Under Siege “
By Robert F. Carline, Rebecca L. Dunlap Jason E. Detar, Bruce A. Hollender Has nothing on dissolved oxygen or aquatic insects. In my opinion we need much more of an ecosystems approach for streams (Which we are doing for Little Sandy Creek in N.Y.).
Now back to Ephemeralla subvaria. The title of the paper I published on this project (my first of nearly 300 publications) was:
1. Hall, C.A.S. 1969. Mortality of the mayfly nymph, Ephemerella rotunda, at low dissolved oxygen concentrations. J. Elisha Mitchell Sci. Soc. 85(1): 34-39 (M.S. Thesis, Pennsylvania State University, 1966).
Whoa! Ephemeralla rotunda? This was by far the most abundant mayfly in Spring Creek where I sampled! But I could not even find the name in your list. Also I had my samples verified by Burke, author of the authoritative "Mayflies of Illinois", and he said Well that’s what it keyed out to in my book”. (Talk about scientific ass covering! ) Well to make matters worse (as of 24 hours ago) my next girlfriend, Molly, at the University of North Carolina, loved the name of “Ephemerella rotunda”, the rotund one, which comes to think of it described her as well. I liked it too. But n’exist plus: where had the most abundant mayfly gone? Fortunately upon reading the rest of the post I found “Ephemerella invaria is one of the two species frequently known as Sulphurs (the other is Ephemerella dorothea). There used to be a third, Ephemerella rotunda, but entomologists recently discovered that invaria and rotunda are a single species with an incredible range of individual variation." Ahh neither rotunda nor Molly stood the test of time. So I assume what I called rotunda is still alive and well in Spring Creek as invaria. Again, can anyone verify that?
If anyone wants to follow up on the distribution and abundance of mayfly (or any other species) may I recommend: Hall, C.A.S., J.A. Stanford and R. Hauer. 1992. The distribution and abundance of organisms as a consequence of energy balances along multiple environmental gradients. Oikos 65: 377-390. I can send it if you cannot get it from google, which I think you can. (chall@esf.edu)
So is Ep Infrequens now known as Ep Dorothea?
20 replies
Posted by Wbranch on Feb 17, 2008 in the species Ephemerella dorothea infrequens
Last reply on Jul 1, 2014 by Crepuscular
These mayflies look more like the Sulfurs I see on the Delaware system than the PMD's I see in Montana. The Montana mayfly has a distinct yellow leading edge to an overall light dun gray wing and the abdomen and thorax have a more light greenish/yellow cloration so how is it that Infrequens is now known as Ep Dorothea Dorothea?
Drunella cornuta on the Brodhead at Stroudsburg PA
11 replies
Posted by Reify on Apr 21, 2014 in the species Drunella cornuta
Last reply on Apr 24, 2014 by Brookyman
4/21/14 - Fished the Brodhead today at the last park before last bridge on PA 191 - downstream of huge riffle section so is a great tretch for this species. I didn't get there until around 1:00 PM, took a nap and started fishing at 2:00 and there were still cornuta coming off sparsely but steadliy - until 3:30 PM. Sparse rises, but I was entertained. Is that normal or could it be because the water is unusually cold this year. Are the males and females of the same size or is one larger - and of slightly more pale coloration at take-off from surface? It almost looked to me to be two different flies, but I'm sure they weren't.
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 Ephemerellidae
References
- Arbona, Fred Jr. 1989. Mayflies, the Angler, and the Trout. Nick Lyons Books.
- Caucci, Al and Nastasi, Bob. 2004. Hatches II. The Lyons Press.
- Jacobus, L. M., Wiersema, N.A., and Webb, J.M. 2014. Identification of Far Northern and Western North American Mayfly Larvae (Insecta: Ephemeroptera), North of Mexico; Version 2. Joint Aquatic Science meeting, Portland, OR. Unpublished workshop manual. 1-176.
- Leonard, Justin W. and Fannie A. Leonard. 1962. Mayflies of Michigan Trout Streams. Cranbrook Institute of Science.
- 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.
Mayfly Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)
Taxonomy
Genus in Ephemerellidae
Attenella
7
39
Caudatella
6
20
Dannella
0
0
Dentatella
0
0
DrunellaBlue-Winged Olives
53
292
EphemerellaHendricksons, Sulphurs, PMDs
159
822
EurylophellaChocolate Duns
29
153
Matriella
0
0
Penelomax
3
25
Serratella
3
21
TeloganopsisLittle black Quills
1
6
Timpanoga
3
11
Genus in Ephemerellidae: Attenella, Caudatella, Dannella, Dentatella, Drunella, Ephemerella, Eurylophella, Matriella, Penelomax, Serratella, Teloganopsis, Timpanoga
2 genera (Caurinella and Tsalia) aren't included.