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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

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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Report at a Glance

General RegionMaryland, USA
Specific LocationBeaver Creek
Dates FishedMarch 28
Time of Day2-6 pm
Fish Caughttrouts
Conditions & Hatchessunny, 45 F, clear water at 50 F, sparse BWOs, later plentiful midges, tiny pale mayflies (#28 or so), and even a larger yellow mayfly (#16)

Details and Discussion

CaseyP's profile picture
Arlington, VA/ Mercersburg, PA

Posts: 653
CaseyP on Mar 28, 2011March 28th, 2011, 1:05 pm EDT
colder than a brass monkey's toes this AM in central PA so i headed south, figuring by the time i got there it would have warmed above freezing, and it did. bought a MD license and celebrated Spring with a stop at Beaver Creek. not much action on the nymph front, but then the BWOs started up sparsely and one or two fish responded. caught one stocked rainbow, one wild brown, one holdover rainbow on an Adams. thank you for the chance to share--next time will bring camera. figured net was enough bad luck this time around.

BTW, there is a crackerjack new fly shop there now in the country store building.
"You can observe a lot by watching." Yogi Berra
Troutnut's profile picture
Bellevue, WA

Posts: 2758
Troutnut on Mar 28, 2011March 28th, 2011, 6:26 pm EDT
Congrats! Always good to get out on liquid water after a long winter. Still waiting for some sign of spring here.

At least the days are getting long. It's not dark til 9:30 at night, but everything's still frozen over.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Jmd123's profile picture
Oscoda, MI

Posts: 2474
Jmd123 on Mar 29, 2011March 29th, 2011, 5:59 am EDT
Good job, CaseyP! Be sure to take that camera next time. The good old Adams is one of my go-to flies. Can't wait to throw a few myself, but I am a-waiting on the weather...

Hang in there Jason. My flyrodding expeditions are stalled due to cold weather and ice as well. You have my sympathies!

No matter how big the one you just caught is, there's always a bigger one out there somewhere...

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